Violence in Syria has killed eight people, activists say, even as a UN mission charged with overseeing a battered truce neared half its planned strength.

In the northwestern province of Idlib, security forces killed a man and a woman during a series of raids, activists said on Saturday.

Also in the province, a UK-based rights group said four soldiers were killed in clashes between armed rebel groups and government forces in Hantuten village.

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"Violent clashes are raging between Syrian regime forces and armed military defectors ... The sounds of strong explosions were heard followed by security forces using heavy and medium machinegun fire," the Syrian Observatory for Human Rights said.

In the central Hama province, a civilian was reportedly killed in pre-dawn shelling of the village of Mork.

Another civilian was killed by sniper fire in the northeastern city of Deir al-Zor, activists said.

The persistent violence came as the UN mission in Syria said it now had 145 military observers on the ground, just shy of half the force of 300 authorised by the Security Council. They are backed by 56 civilian staff.

The observers are tasked with shoring up a promised ceasefire brokered by UN-Arab League peace envoy Kofi Annan that was supposed to take effect on April 12 but which has been broken daily.

Damascus activists detained

Meanwhile, in Damascus, people on Saturday attended funerals for victims killed in Thursday's bomb attack at al-Othman mosque.

Two suicide car bombers killed 55 people and wounded 372 in Damascus, state media said, the deadliest bomb attacks in the Syrian capital since an uprising against President Bashar al-Assad began 14 months ago.

Also in Damascus, ten activists who held a peaceful demonstration in front of the citadel in the Old City on Saturday evening were arrested.

The protest, part of an initiative called Stop the Killings, was held to commemorate the victims of the latest bombings. 

More than 11,000 people have died in the unrest that began in March 2011, according to activist groups.

Source: Agencies