Arab League chief Nabil al-Arabi said on Monday that snipers and gunfire remain in Syrian cities and called for an immediate halt to the shootings, in his first remarks since Arab monitors were deployed.

"There is gunfire. There must be a total halt to the gunfire," the League chief said, in the face of mounting criticism of the hard-won observer mission's failure to stem the persistent bloodshed.

Arabi charged that snipers were still deployed on rooftops in protest centres threatening the lives of civilians, even as monitors try to end the Syrian government's deadly crackdown that has claimed thousands of lives since March.

But "it is difficult to say who is firing on whom," Arabi told a news conference at Arab League headquarters in Cairo.