Clashes between government troops and army deserters raged on Sunday across Syria, where at least 31 people were killed and more than 200 arrested, activists and monitors said.

The weekend escalation in violence came ahead of a UN deadline of Tuesday for regime forces to cease fire, prompting harsh words from international envoy Kofi Annan who said the escalation was "unacceptable."

In the Damascus province village of Beit Jin, five deserters were killed in clashes with government troops as army helicopters flew overhead and loud blasts rang out, the Syrian Observatory for Human Rights reported.

The Britain-based monitoring group said two other deserters were killed in the northwestern province of Idlib and in Aleppo in the north, while 12 regime soldiers died in other fighting across the country.

At least 12 civilians were also killed on Sunday, including eight in the Idlib region where regime forces, backed by helicopters, carried out a largescale operation east of the town of Jisr al-Shughur.

A civilian was shot dead near the Lebanese border, while another two died in the central province of Homs and one was killed by gunfire as troops raided the southern Daraa province looking for suspects, it reported.

According to the monitoring group, 200 people were arrested across Syria by regime forces as they pressed on with a bloody campaign to crush dissent.

Raids were carried out in the Idlib region of Kafar Nubul, where regime forces, under cover of intense fire, arrested dozens after government troops clashed with fighters of the rebel Free Syrian Army, activists said.

Clashes also broke out between deserters and security forces on Saturday night in the Damascus neighbourhood of Barzeh.

"Security forces stormed Barzeh under cover of darkness, searched homes and arrested several people," activist Dib al-Dimashqi told AFP via Skype.

Security forces also deployed in the central Hama province town of Murk where they "torched houses and cars and arrested several people," said another activist, Abu Ghazi al-Hamwi.

Fourteen people were also arrested in the eastern oil province of Deir Ezzor, activists said.

According to the Observatory, violence on Saturday killed 128 people across Syria, including 86 civilians, half of them in the town of Latamna near Murk.