Two men were killed and more than 20 injured when Syrian government forces shelled a Palestinian refugee neighborhood in Damascus, activists said.

A group based in the al-Yarmouk camp, the Yarmouk committees -- Syrian revolution, said regime troops fired mortars at Al-Waseem mosque, causing the casualties.

The shelling took place after hundreds of people returned to the camp, having fled in late 2012 as fighting intensified in the area, the group said.

In December, heavy fighting broke out in Yarmouk between Syrian rebels and the army, causing Palestinians to flee.

PLO leaders say they are working on a deal to demilitarize the camp with the Free Syria Army and Syrian government forces.

Syria hosts half a million Palestinian refugees, descendants of those admitted after the creation of Israel in 1948.