Violence has killed more than 15,000 people in Syria since a revolt erupted last year against the regime of President Bashar al-Assad, the Syrian Observatory for Human Rights said on Thursday.

At least 10,480 civilians, 3,715 soldiers and 830 army defectors have been killed in the crackdown and in clashes since March last year, said the Observatory, which counts those who have taken up arms against the regime as civilians.

"If the international community remains silent and happy to just observe the situation, more blood will flow in Syria," the Observatory's Rami Abdel Rahman told AFP.

"The violence has only become worse in the past two months, and will become more bitter," he added.

An escalation of violence has pushed a team of nearly 300 UN observers in Syria to suspend their operations, although they remain in the strife-torn country.

On Thursday, at least 46 people were killed in violence across Syria, where President Bashar al-Assad's regime has been waging a brutal crackdown on dissent since an Arab Spring-inspired uprising erupted in mid-March 2011.

At least 13 civilians were killed in the flashpoint central city of Homs and another two unidentified people died in nearby Quasyr, the Observatory's Rami Abdel Rahman told AFP.

Elsewhere, eight soldiers and a rebel were killed in heavy fighting at Armanaz, near Turkey in the northwestern province of Idlib, following a rebel attack on an army barracks, said the Britain-based group.

In the southern province of Daraa, cradle of the uprising, at least 10 people were killed as the town of Inkhel was shelled and stormed by troops who then carried out a series of raids.

A total of 17 government troops were killed on Thursday.

The fresh bloodshed comes a day after violence cost the lives of 98 people across the country, including 53 civilians, 35 soldiers and 10 rebel fighters, according to the Britain-based watchdog.