Around 20 people are reported to have been killed by shelling from government forces in Syria. 

Eight of the reported casualties in the Raqqa province are said to have been children.

Separately, the commander of Syria's military police has defected from the army.

He is reported to have declared allegiance to the uprising against President Bashar al-Assad, according to a video and a Syrian security source.

It comes as opposition fighters continued to gain ground in battles against regime forces across the country.

He is the highest ranking military police officer to defect since the start of the conflict in Syria nearly two years ago.

Wearing a camouflage uniform with red officer insignia on the shoulder, General Shalal spoke from a desk in a room in an undisclosed location.

Some rebel sources said he had fled to Turkey. It was not clear when the officer changed sides.

A Syrian security source confirmed the defection but played down its significance.

"Shalal did defect but he was due to retire in a month and he only defected to play hero," the source said.

Elsewhere, Syrian President Bashar al-Assad has sent a senior diplomat to Moscow to discuss proposals to end the conflict convulsing his country made by international envoy Lakhdar Brahimi, Syrian and Lebanese sources said.

Mr Brahimi, who saw Assad last Monday is planning to hold a series of meetings with Syrian officials and dissidents in Damascus this week.

He is trying to broker a peaceful transfer of power, but has disclosed little about how this might be done.

Deputy Foreign Minister Faisal Makdad flew to Moscow to discuss the details of the talks with Brahimi, said a Syrian security source, who would not say if a deal was in the works.

However, a Lebanese official close to Damascus said Makdad had been sent to seek Russian advice on a possible agreement.

He said Syrian officials were upbeat after talks with Brahimi, the UN-Arab League envoy, who met Foreign Minister Walid Moualem yesterday a day after his session with Assad, but who has not outlined his ideas in public.

Russia, which has given Assad diplomatic and military aid to help him weather the 21-month-old uprising, has said it is not protecting him, but has fiercely criticised any foreign backing for rebels and, with China, has blocked UN Security Council action on Syria.