The U.S. military said Tuesday it lost contact with a unarmed drone that was being remotely piloted over Syria, but could not corroborate reports that it was shot down.
The Pentagon statement came after Syria's state-run SANA news agency said the Syrian military shot down a drone conducting a surveillance mission in Latakia province, along the Mediterranean coast.
If the report is true, it would be the first U.S. aircraft shot down over Syria since a U.S.-led coalition battling Islamic State in Iraq expanded airstrikes into Syria in September.
Earlier on Tuesday, Amnesty International released a new report saying Syrian forces killed civilians in airstrikes on the northern town of Raqqa last November in attacks that violated human rights law.
The report presents accounts of airstrikes on separate days that killed 115 civilians, including 14 children.
Amnesty spoke by phone or Skype with witnesses to the attacks and local activists. They described airstrikes that hit areas that had no military targets nearby or ones where civilians were killed in places where Islamic State militants were known or likely to be.
Amnesty said those attacks amount to either direct attacks against civilians, indiscriminate bombings or disproportionate strikes -- all of which are barred under international human rights law.
Raqqa is a stronghold of the Islamic State group, but Amnesty said that does not give the government a reason to bomb the city as if the area were populated solely by the militants.
"Syrian government forces have shown flagrant disregard for the rules of war in these ruthless airstrikes," Amnesty's Philip Luther said. "Some of these attacks give every indication of being war crimes.
"They have carried out repeated attacks on civilian areas without clearly identifying military targets, a blatant violation of the requirement to distinguish between civilians and military targets," he added.
Gas attack allegation
Also Tuesday, the Britain-based Syrian Observatory for Human Rights accused Syrian government forces of dropping barrel bombs filled with poison gas on the town of Sarmin in Idlib province, killing six people and injuring dozens more.
The government denied the reports.
Independent investigators on war crimes in Syria Carla del Ponte and Paulo Pinheiro chat at the U.N. Human Rights Council in Geneva, March 17, 2015.
Meanwhile, the head of the United Nations commission of inquiry on Syria said Tuesday that the investigators are prepared to release the names of those on its list of accused human rights violators.
The commission released its latest report on the conflict, saying it has resisted publishing its private list of accused abusers, but that to continue keeping it secret would reinforce the impunity present in Syria.
"We will share names and information about specific alleged perpetrators with state prosecution authorities that are preparing cases to be heard before a competent and impartial judiciary," said commission head Paulo Pinheiro. He specified the names would not be made public.
Russia and China have each vetoed multiple draft Security Council resolutions on Syria since the conflict there began in March 2011.
'Shock the conscience'
The commission report said that without a consensus for action on the council, there should be consideration for creating an international tribunal to address war crimes allegations.
"That perpetrators have, for more than four years, committed crimes that shock the conscience of humanity raises questions about the inadequacy of the response of the international community," it said.
More than 200,000 people have been killed in the Syrian conflict, which began in 2011 with protests against the rule of President Bashar al-Assad and has driven 3.9 million Syrians to flee their shattered homeland.
Pinheiro said his team would share information from “our extensive database” to aid domestic investigations and prosecutions. Some countries have “universal jurisdiction,” which means they can prosecute crimes committed by foreign nationals abroad.
The investigators said their lists, kept in a U.N. safe, include military and security commanders, the heads of detention facilities and commanders of insurgent groups. They are based on their interviews with hundreds of victims and witnesses.
Syria's ambassador Hussam Edin Aala responded angrily at the 47-member forum to the investigators' move.
“The commission's biased and selective approach and its continued accusations toward the government of Syria while turning a blind eye to crimes of terrorist groups such as the Nusra Front ... leads us to doubt the credibility, the motives," Aala said.
Some material for this report came from Reuters and AP.