At least 22 people were killed by Syrian security forces on Saturday, the opposition said, hours before the Arab League was to meet to discuss enforcing unprecedented sanctions on Damascus.

In the dissident province of Idlib near the Turkish border, clashes on Saturday between army defectors and the military resulted killing 15 people, three of them civilians, reported the Syrian Observatory for Human Rights.

An officer was among seven members of the military killed in the four-hour fight, the London-based observatory said. Five army defectors were also among the dead, it added.

Over the past few weeks, army personnel who have defected to the opposition, have claimed to have killed more than 25 soldiers in attacks on military facilities.

In the southern province of Daraa, another focal point of anti-government dissidence, one civilian was shot dead and five wounded on Saturday by military forces in a crackdown on the town of Tafas, the observatory said.

Meanwhile, four civilians were shot dead by government forces in the restive central province of Homs, activists said.

Two more civilians were killed by sniper fire in the town of Al-Rastan also in Homs, reported the Syrian Observatory for Human Rights.

A new report by the UN High Commissioner for Human Rights, Navi Pillay, has said more than 4,000 people have been killed in Syria since March.

However, Michel Kilo, a prominent Syrian opposition figure, contested the death toll figures issued by the UN.

"More than 10,000 have been killed in Syria since the uprising started in mid-March," Kilo told the broadcaster Al-Arabiya on Saturday.

It is hard to verify news from Syria, as authorities have barred most foreign media from the country.

An Arab League committee was due to meet in Doha later on Saturday to discuss the implementation of sweeping sanctions imposed by the regional bloc on Syria for its failure to halt a deadly clampdown on opposition.

Led by Qatar, the committee comprises foreign ministers of Algeria, Egypt, Oman and Sudan.

During talks in Cairo on November 27, the League agreed to halt transactions with the Syrian central bank, freeze government assets and suspend investments in Syria after the regime of President Bashar Assad ignored a deadline to implement a peace plan.

Damascus has called the measures "a declaration of economic war."