On the A9 highway that runs from the south to the northern tip of Sri Lanka, we left the last military checkpost, and crossed to the office where the Liberation Tigers of Tamil Eelam processed our documents to enter Vanni, the area under their control.

This was 2002 and those few steps felt like they separated two different nations. Most of Sri Lanka was a familiar democracy. A feisty media, activists who hotly debated rights issues, citizens with varied political loyalties, discussions of economic opportunities, a sense of a nation poised for great things. It seemed to be held back only by the brutal two-decade-long civil war between Sri Lankan government forces and the separatist Tamil Tigers, led by Vellupillai Prabhakaran.

In contrast, the signs of what an independent Tamil Eelam might look like were frightening. Images of the Thalaivar (Great Leader) Prabhakaran appeared everywhere. His soldiers were ever present, and so were his informers. Access to all facilities, health, food, livelihood or education was determined by the LTTE cadre. The media sang a single tune, celebrating the glory of the Tamil Tigers.

Villagers whispered their complaints, often dragging us into secluded corners so they would not be overheard. There was no freedom to travel outside the zone controlled by the LTTE without leaving family members behind as hostage, they told us. Parents mourned children entering their teens, because they would soon be drafted into battle. Plenty had already lost loved ones. There was no space at all for questions or dissent.

We were there for Prabhakaran's press conference. It was apparent that the man who had engineered thousands of brutal deaths suffered little remorse. He was unwilling to consider that there was any need for accountability for human rights abuses, convinced that his was a just fight. And many believed that he could succeed. He had access to weapons and money. And apparently, he had friends.

By May 2009, though the situation had changed drastically. Prabhakaran and most of his top leaders were dead, vanquished in a determined push by the Sri Lankan military. It had taken a little over three years of intense bloody battle. For most Sri Lankans, it was time to hope that the country could embark upon a peaceful and prosperous future.

What was expected was that the freedom of the south would enter the north. But sadly, Sri Lanka seems headed in the wrong direction. Prabhakaran may have lost the battle, but it is his culture of fascist dominance, personality-based politics, paranoid and aggressive self-promotion, and an absolute disregard for accountability that now dominates Sri Lanka.

President Mahinda Rajapakse waves to the masses from billboards. Journalists and critics have met with the same fate that once prevailed in Prabhakaran's world: Arrest, torture, murder, "disappearance". The democratic institutions that separate the country from Prabhakaran's nightmare - the courts, independent civil society and Opposition political parties - are under increasing pressure.

Dissent has been so effectively silenced that people now whisper their complaints. Only one media tune is encouraged, the one that celebrates government glory. Any effort to demand accountability for alleged violations during the military operation that ended the civil war in May 2009 is dismissed as enemy propaganda. And the government believes it can do this, as the Sri Lankan envoy to the UN blithely declared: "We have friends".

At the heart of the human rights debate in Sri Lanka are allegations that war crimes occurred during the fighting, especially the final months of the war.

Unsurprisingly, the Tamil Tigers were responsible for numerous violations. They had used civilians as "human shields" against attack, shot civilians as they tried to flee LTTE control, deployed artillery near civilians, forcibly recruited children as soldiers and conducted numerous suicide attacks.

But the government forces are also alleged to have committed terrible atrocities, including widespread and indiscriminate shelling of civilians and attacks on hospitals. They deliberately deprived civilians caught in the war zone of humanitarian aid. When the fighting ended in May 2009, the government locked up 300,000 Tamil civilians in detention camps for months under poor conditions. Several were forcibly disappeared after they were detained by government forces and there is gruesome video-evidence of some government soldiers summarily executing detainees, including people the military had reported were killed in combat.

A new report to the United Nations Secretary-General confirms the atrocities and blames both sides for the carnage and recommends an international mechanism to ensure justice and accountability. The experts' report concludes that both the government and the Tamil Tigers conducted military operations "with flagrant disregard for the protection, rights, welfare and lives of civilians and failed to respect the norms of international law".

While the government's denial of independent access to the battlefield means no one knows for sure how many people died, the report says the number is thought to be in the tens of thousands. "[M]ultiple sources of information indicate that a range of up to 40,000 civilian deaths cannot be ruled out at this stage," the report says.

The report, a careful and professional study by a panel of three internationally recognised experts, should have been taken seriously. Instead, the government called the report "illegal" and "biased, baseless and unilateral".

President Rajapakse called for demonstrations to show solidarity with the armed forces, and began a diplomatic campaign to pressure the UN not to act on the panel's recommendations.

That is because the one thing the government has not done is to investigate allegations against its military operation. The panel of experts looked closely at government steps to provide accountability.

What they found were blanket denials. The government maintains that it conducted a "humanitarian rescue operation" with a policy of "zero civilian casualties". High-ranking government officials, including President Rajapakse and his brother Gotabaya, the defence secretary, have repeatedly denied that government forces caused civilian casualties. Foreign minister G.L. Peiris even suggested that the experts' report will endanger post-conflict reconciliation and rehabilitation.

The government last year established a Lessons Learnt and Reconciliation Commission, which it frequently touts as an accountability mechanism. But the panel of experts did not take the bait - their report concludes the commission is "deeply flawed" and "does not meet international standards for an effective accountability mechanism".

Certainly the previous commissions of inquiry established by the Sri Lankan government failed to deliver justice. In fact, in 2008, an international group of experts established to oversee one such investigation quit in dismay, saying that proceedings "have fallen far short of the transparency and compliance with basic international norms and standards pertaining to investigations and inquiries."

One reason the government forces were eventually able to prevail after 26 years was because the LTTE had lost its friends. Supporters of minority rights in Sri Lanka were dismayed by the group's rampant abuse of human rights, including recruitment of children into combat and extortion from expatriate Tamil communities. By the end, the LTTE was proscribed as a terrorist group in many countries, affecting funding and assistance from the Tamil diaspora.

Sri Lanka has now called upon its "friends" to shield it from an international investigation into alleged human rights violations. The international community largely stood by while the bloodbath took place and as the Sri Lankan government refused to investigate the war crimes allegations. It is crucial for Sri Lanka's friends to speak up and join other governments to press for an international investigation that can bring genuine justice.

In particular, it is important for India, China and Japan to speak out. These countries have been Sri Lanka's faithful allies and are supporting the post-conflict reconstruction efforts; and that is precisely why they should speak up. But China and Russia have indicated they want to protect Sri Lanka from an international inquiry. India and Japan argue that they are more influential with Sri Lanka as they refrain from outspoken criticism of the government's abuses.

India has not only been silent about Sri Lanka's abysmal treatment of its citizens, but it has also actively prevented greater international scrutiny and pressure. Shortly after the fighting ended, India voted for a Human Rights Council resolution congratulating the Sri Lankan government for its victory, thus helping to defeat an alternative resolution calling for an investigation of credible allegations.

India has already paid a heavy price for trying to bring peace in Sri Lanka, losing over 1,000 soldiers who were on a peacekeeping mission in the late 1980s. Rajiv Gandhi was assassinated by the Tamil Tigers.

Now India has a new opportunity to promote justice for Sri Lanka's war victims. Instead of being on the side of the abusers, India should be working alongside those governments that wish to see that the people responsible for terrible crimes are held to account. India should not hold back now. By speaking up, it can ensure that the Sri Lankan people, Sinhalese and Tamil and the rest achieve a future they have long craved, one that allows all the promise of a peaceful democracy.

Meenakshi Ganguly is the South Asia director in the Asia Division of Human Rights Watch.