Gun battles and shelling hit the Palestinian camp of Yarmuk in southern Damascus on Sunday, breaking a truce in place since mid-February, said a group that monitors the Syrian conflict.

"There was shelling of Yarmuk and fighting between (Al-Qaeda branch) Al-Nusra Front and the Popular Front for the Liberation of Palestine-General Command," said the Syrian Observatory for Human Rights.

"The truce has been broken," its director Rami Abdel Rahman told AFP.