Human Rights Watch demanded Thursday that the U.S. government investigate a drone strike that killed 12 people in Yemen during a December wedding procession, saying it may have violated international law, Al Arabiya reported.
The attack raised "serious concerns" about whether U.S. forces were abiding by stricter rules recently announced by President Barack Obama for drone attacks, the group said.
A dozen men were killed and 15 other people wounded, including the bride, when four Hellfire missiles struck a convoy of 11 vehicles at a wedding celebration on December 12 near the central town of Radaa, according to the New York-based rights group.
Although U.S. and Yemeni officials said the dead belonged to al-Qaeda in the Arabian Peninsula, witnesses and relatives told Human Rights Watch that all the casualties were civilians and not AQAP fighters.
"The U.S. refusal to explain a deadly attack on a marriage procession raises critical questions about the administration's compliance with its own targeted killing policy," said Letta Tayler, author of the 28-page report.
"All Yemenis, especially the families of the dead and wounded, deserve to know why this wedding procession became a funeral."
In a speech in May, Obama said U.S. policy for the "targeted killing" program requires "near-certainty" that no civilians will be harmed in a drone attack against al-Qaeda members.
Human Rights Watch called on the Obama administration to launch a formal investigation of the strike, publish the findings and hold accountable any official suspected of wrongdoing.
The attack may have violated the laws of war by failing to distinguish between combatants and civilians, or by causing civilian losses out of proportion to the expected military advantage, the report said.
The U.S. government has yet to publicly acknowledge the missile attack.
In the hours after the strike, security officials in Yemen told AFP that some of the dead were Al-Qaeda militants, while others were civilians in a wedding procession.
The missiles destroyed a pickup truck in the procession, according to the report.
"Witnesses and a Yemeni government source said three or four men fled the truck before it was struck," Human Rights Watch said.
US officials had privately said a terror suspect on a "most wanted" listed was targeted in the attack but was not killed.
The local governor and military commander called the attack a "mistake" and gave money and assault rifles to the families of those killed and wounded -- a traditional gesture of apology in Yemen, the report said.
Estimates vary about the number of people killed by the US drone strikes in Yemen.
The New America Foundation, a Washington think tank that has tried to keep a tally based on "credible news reports," says about 608 to 793 militants have been killed in 99 drone strikes in Yemen since 2002, as well as 78 to 84 civilians