An Israeli soldier stands guard aboard a naval vessel as Gaza-bound ships are intercepted in the Mediterranean Sea on May 31, 2010.

(New York) – Israel should promptly conduct a credible and impartial investigation into the deaths of at least 10 activists after Israeli security forces boarded ships that were part of an “aid flotilla” to Gaza, Human Rights Watch said today.

Human Rights Watch said that the incident, in which dozens of activists and several Israeli commandos were also reportedly wounded, raises grave concerns about possible unlawful and excessive use of lethal force.

“A prompt, credible, and impartial investigation is absolutely essential to determine whether the lethal force used by Israeli commandos was necessary to protect lives and whether it could have been avoided,” said Sarah Leah Whitson, Middle East director at Human Rights Watch. “Given Israel's poor track record of investigating unlawful killings by its armed forces, the international community should closely monitor any inquiry to ensure it meets basic international standards and that any wrongdoers are brought to justice.”

According to reports, at 4 a.m. on May 31, Israeli commandos boarded ships of the aid flotilla. Approximately 700 activists were taking part in the 6-ship flotilla. The flotilla’s organizers said it was carrying humanitarian aid intended for Gaza, including cement, wheelchairs, and parts to repair water infrastructure. The activists said the ships were 70 nautical miles offshore when Israeli forces boarded the ships.

The Israeli government stated that activists on the ships violently resisted Israeli boarding forces, seriously wounding two soldiers. Activists aboard the ships stated that Israeli forces killed unarmed members of the humanitarian aid flotilla. Human Rights Watch has not yet been able to conduct its own investigation to determine which account is accurate. The government had warned the flotilla not to attempt to breach Israel’s blockade of Gaza.

“The Israeli government’s opposition to the flotilla initiative was well advertised, but does not address the main issues – did Israeli forces use unlawful lethal force aboard the ships, and could alternative steps have been taken that would have avoided the violence,” Whitson said.

Human Rights Watch called on Israel to grant all detained and injured flotilla members immediate access to counsel and their families, and to disclose the identities of all those injured and killed. According to the flotilla’s organizers, Israeli authorities have denied those detained in Ashdod port access to their lawyers, and have yet to disclose where the injured have been hospitalized. All communications from the flotilla and flotilla members have apparently been blocked, and the names of those killed have not been released.

Israel has blockaded Gaza's land and sea borders since Hamas seized control of the territory in June 2007. Egypt has been an essential partner in the blockade along Gaza’s southern border. The blockade, which amounts to the unlawful collective punishment of Gaza's civilian population, has severely damaged the economy, leaving 70 to 80 percent of Gazans in poverty and dependent on humanitarian aid.

The United Nations Basic Principles on the Use of Force and Firearms by Law Enforcement Officials provide that authorities shall, as far as possible, apply non-violent means before resorting to the use of force and firearms. The Principles provide that if the lawful use of force and firearms is unavoidable, then the authorities must use restraint and act in proportion to the seriousness of the offense. Lethal force may be used only when strictly unavoidable to protect life. The Basic Principles also call for an effective reporting and review process, especially in cases of death and serious injury.