U.S. Secretary of State John Kerry hosts his British counterpart for talks Wednesday on Syria, as activists report anti-government rebels killed dozens of Shi'ites in a town in eastern Deir el-Zour province.
The Syrian Observatory for Human Rights, a pro-opposition monitoring group that has reported abuses on both sides of the conflict, said most of the 60 victims in the town of Hatla late Tuesday were pro-government Shi'ite militiamen.
A video posted online by rebels showed dozens of gunmen carrying black Islamist flags celebrating and firing guns as smoke curled above several buildings in Hatla. The Observatory said rebels secured control of the town and burned down a number of houses in the Shi'ite district. Shi'ite civilians then fled.
A Syrian government official denounced the attack, calling it a "massacre" of civilians.
In Washington, Kerry and British Foreign Secretary William Hague will consider potential steps to achieve their goal of establishing a transitional government in Syria to lead the country out of more than two years of turmoil.
Both Britain and the United States have provided non-lethal support to rebels opposed to Syria's President Bashar al-Assad, and have discussed the possibility of sending weapons.
The White House said Tuesday that arming the rebels remains one option President Barack Obama is considering as he weighs a range of possible actions related to Syria.
White House Press Secretary Jay Carney said the United States and its international partners continue to pursue a Syrian peace conference, but that the ongoing violence means they must also explore aiding the opposition.
Mr. Obama has ruled out any intervention that would require U.S. military forces inside Syria.
Meanwhile, Human Rights Watch is urging both the opposition and the Syrian government to allow humanitarian aid to freely flow to civilians inside Syria.
In a statement Wednesday
, the rights group said the United Nations must also do more to help get aid across the border from Turkey into northern Syria.