Syrian regime warplanes and troops have blasted away at rebels close to Damascus, the day after a car bomb in a mainly Alawite northern district of the capital killed at least 11 people, a watchdog said.

Fighter-bombers were hitting Duma, northeast of Damascus, on Friday and army artillery was shelling the southwestern Daraya neighbourhood which the rebels have led against regime assaults for weeks, the UK-based Syrian Observatory for Human Rights said.

Troop reinforcements were being sent to Daraya, the British-based group added.

Also on Friday, Syria slammed as "biased" a separate UN report released December 20 that called the conflict in the country "overtly sectarian in nature."

The Syrian foreign ministry accused the UN of a "lack of professionalism" in producing its report, and said that any sectarian dimensions to the conflict were because of foreign support for "armed groups," state news agency SANA said.

In response to the UN finding that "entire communities" were at risk from the civil war, the ministry pointed to the historic coexistence of Syria's various ethnicities and religions, saying the regime was battling "terrorist groups financed from abroad."

Nationwide on Friday at least 27 people died -- 16 civilians and 11 rebels -- according to preliminary figures given by the Syrian Observatory for Human Rights.

Petrol station blast

On Thursday, in the north Damascus neighbourhood of Massaken Barzeh, at least 11 people were killed and 40 wounded after a car bomb exploded at a crowded petrol station, opposition activists said.

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The station was packed with people queuing for fuel that has become increasingly scarce during the country's 21-month-long insurgency aimed at overthrowing President Bashar al-Assad.

The semi-official al-Ikhbariya television station on Friday showed footage of 10 burnt bodies and Red Crescent workers searching for victims at the site.

The opposition Revolution Leadership Council in Damascus said the explosion was caused by a booby-trapped car.

There was no immediate indication of who was responsible for the bombing in the Barzeh al-Balad district, whose residents include members of the Sunni Muslim majority and other religious and ethnic minorities.

"The station is usually packed even when it has no fuel," said an opposition activist who did not want to be named.

"There are lots of people who sleep there overnight, waiting for early morning fuel consignments."

It was the second time that a petrol station has been hit in Damascus this week.

Dozens of people were incinerated in an air strike as they waited for fuel on Wednesday, according to opposition sources.

Masakin Barzeh is a middle-class neighbourhood northeast of downtown that is home to many government employees.

More than 60,000 people have been killed in the uprising and civil war, the United Nations said this week, a much higher death toll than previously thought. 

Source: Agencies