The US has urged countries to cut trade ties with Syria in an attempt to raise pressure on President Bashar al-Assad’s government to halt its continuing clampdown on pro-democracy demonstrators.

"We urge those countries still buying Syrian oil and gas, those countries still sending Assad weapons, those countries whose political and economic support give him comfort in his brutality, to get on the right side of history," US Secretary of State Hillary Clinton told reporters on Friday.

Her comments came as large anti-government protests continued across Syria despite a harsh security crackdown.

Human rights activists said at least 16 people were killed on Friday amid a major assault by security forces.

Protesters reportedly came under fire in the central city of Homs, Hama, the capital Damascus, Deir al-Zour in the east and Aleppo and Idlib near Turkey's border.

European diplomats estimated in a UN Security Council meeting earlier this week that 2,000 people had been killed - mostly civilians - and a further 3,000 had disappeared since an uprising against President Assad’s rule began in March.

Thousands have also fled across the border to neighboring Turkey.

US calls for unified global stance

The US has imposed sanctions on Syria and has urged other countries to widen sanctions. But Washington has stopped short of calling for Assad to stand down, instead appealing for a more unified global stance on Assad’s crackdown on civilians.

"It's important that it's not just the American voice. And we want to make sure those voices are coming from around the world," Clinton said in an interview with US broadcaster CBS.

"We want to see Europe take more steps in that direction, and we want to see China take steps with us. There's no doubt in anyone's mind where the United States stands."

Clinton reiterated the view that Assad has "lost the legitimacy to lead and it is clear that Syria would be better off without him."

On Thursday, the US State Department said their ambassador in Damascus, Robert Ford, had warned Foreign Minister Walid Muallem of further sanctions unless the Syrian government ended its crackdown.

"[Ford] made clear, as we have publicly, repeatedly, that Syria is going to face increasing pressure if the violence doesn't end, including more economic sanctions from the US and, we hope, from others," State Department spokeswoman Victoria Nuland told reporters in Washington.

Saudi Arabia, Bahrain and Kuwait have all recalled their ambassadors from Damascus while Turkish Foreign Minister Ahmet Davutoglu has described the methods used by the Syrian security forces as "unacceptable."

But UN Security Council veto-holders Russia and China have resisted any tough action against Syria. Both countries often cite the ongoing military mission in Libya as an example of hasty action against Syria could lead to.

Author: Mark Hallam (AFP, Reuters)
Editor: Sonia Phalnikar