Syria - Troops and militiamen loyal to President Bashar al-Assad killed at least 27 young men when they raided villages in a northern Syrian province, an opposition activists' group said on Wednesday.

The young men, all civilians, were mostly shot in the head or chest in their homes or in streets in the villages of Idita, Iblin and Balshon in Idlib province near the border with Turkey, the Syrian Network for Human Rights said.

YouTube videos said to have been taken by local activists in Idlib showed bodies of young men with bullet wounds lying in streets and in houses.

The raids came as the United States appeared to open the door to eventually arming the Syrian opposition, saying that if a political solution to the crisis was impossible it might have to consider other options.

The comments, made by officials at both the White House and the U.S. State Department on Tuesday, marked a shift in emphasis by Washington, which so far has stressed a policy of not arming the opposition and has said little about alternatives.

"We still believe that a political solution is what's needed in Syria," White House spokesman Jay Carney said.

"We don't want to take actions that would contribute to the further militarization of Syria, because that could take the country down a dangerous path. But we don't rule out additional measures."

Asked if the United States was shifting its stance on arming the rebels, U.S. State Department spokeswoman Victoria Nuland said Washington did not want to see the violence increase and was concentrating on political efforts to halt the bloodshed.