The United Nations has said that more than 60,000 people have died in Syria's uprising and civil war.

UN Human Rights Commissioner Navi Pillay said researchers cross referencing seven sources over five months had listed 59,648 people killed there between 15 March 2011 and 30 November 2012.

"The number of casualties is much higher than we expected and is truly shocking," she said.

"Given that there has been no let-up in the conflict since the end of November, we can assume that more than 60,000 people have been killed by the beginning of 2013," Ms Pillay added.

There was no breakdown by ethnicity or information about whether the dead were rebels, soldiers or civilians.

There was also no estimate of an upper limit of the possible toll.

Previously, the opposition-linked Syrian Observatory for Human Rights monitoring group put the toll at around 45,000 confirmed dead but said the real number was likely to be higher.

Meanwhile, around 30 people were killed in a suburb of Damascus suburb after a government air strike hit a petrol station.

Muleiha is a residential and industrial area in the eastern Ghouta region of Damascus that also houses a Syrian air defence base.

Activists said rockets were fired from the base at the petrol station and a nearby residential area after the air raid.

President Bashar al-Assad's forces also fired artillery and mortars at the eastern districts of Douma, Harasta, Irbin and Zamlaka.

His forces control the centre of the capital, while rebels and their sympathisers hold a ring of southern and eastern suburbs that are often hit from the air.

US journalist missing in Syria since November

A US journalist is missing after being kidnapped by unidentified gunmen in northwest Syria six weeks ago.

The family of freelance journalist James Foley, 39, have launched a public campaign to bring him home after requesting a news blackout since he was taken on 22 November in Idlib province.

According to GlobalPost, a news website he had previously reported for, Mr Foley had been driving towards the Syrian border with Turkey when he was intercepted by a car.

He was forced out of his vehicle by two armed men and has not been seen or heard from since, the website said.

Mr Foley is an experienced foreign correspondent and has reported from Syria, Afghanistan and Libya.

He was captured in eastern Libya by government forces in April 2011 and held for 44 days before being released.

He later returned to the country to cover Muammar Gaddafi's fall.