Syrian security forces killed at least 13 people yesterday when they opened fire on anti-regime protests in several parts of the country, a rights group reported.

The Syrian Observatory for Human Rights said eight people were killed when security forces intervened to disperse protests in several suburbs of Damascus including Erbeen and Douma.

Three other people died in the rebellious province of Homs and two in the eastern city of Deir Ezzor, said the Britain-based Observatory.

Activists said “huge demonstrations” rocked Syria yesterday after the weekly Muslim prayers following calls from an Internet group that urged nationwide anti-regime rallies under the banner “death rather than humiliation”.

Meanwhile the European Union yesterday adopted a ban on crude oil imports from Syria as ministers from the 27-nation bloc looked to tighten the screws on the Assad regime at a gathering in Poland.

The sanctions “will go straight to the heart of the regime”, said Dutch Foreign Minister Uri Rosenthal.

The oil embargo, to take effect from today, will deprive Mr Assad’s regime of a vital source of cash. The EU buys 95 per cent of Syria’s crude oil, providing a third of the regime’s hard currency earnings.

Though the loss of the oil will be little felt across the EU, where Syrian crude accounts for a mere 1.5 per cent of the bloc’s imports, Syria has already warned it will find buyers elsewhere.

“We can resolve our problems with the help of China,” central bank chief Adib Mayaleh said in an interview last week. “If the Europeans withdraw the Chinese can easily take their place and fill the vacuum. Russia too can help us.”

While further action to squeeze Damascus was not on the official agenda of the ministers’ two-day talks, EU foreign policy chief Catherine Ashton pledged there would be no let-up in efforts to press Mr Assad to end the regime’s relentless repression.

New sanctions could include a ban on investments in the oil sector, diplomats said.

“Right now it is crucial that we isolate the regime,” said German Foreign Minister Guido Westerwelle, who has been under sharp pressure at home for favouring sanctions over military intervention in Libya.

Westerwelle insisted sanctions would work to force the Assad regime to start a dialogue with dissenters but that the EU needed to work hand-in-glove with regional partners, notably Turkey.