Security forces killed at least three people as they opened fire on protesters who rallied in their tens of thousands across Syria on the last Friday of Ramadan, vowing again to bring down the regime.

A fourth man died yesterday in detention, his family told rights groups.

Spurred by calls posted on the internet, protesters flooded the streets in the north, centre and south of the country, chanting “Bashar, we don’t love you, even if you turn night into day,” according to activists.

The latest bloodletting came as the UN Security Council remained divided over measures against President Bashar al-Assad’s regime, with Russia and China blocking bids to pass fresh sanctions, including a total arms embargo.

The ruler of energy-rich Qatar, Sheikh Hamad bin Khalifa Al-Thani, meanwhile, upped the pressure on Syria during a visit to key Damascus ally Iran, saying the use of force was “fruitless”.

The Syrian Revolution 2011 Facebook group, a motor of the protests since mid-March in defiance of a deadly government crackdown, called the rallies under the banner of “Friday of patience and determination”.

“We will not rest until the fall of the regime,” read the message issued on the last Friday of the Muslim holy month of Ramadan.

Rights activists said at least three people were killed and 25 wounded by security forces and pro-regime militiamen as protesters poured out of mosques, defying a crackdown which the UN says has killed more than 2,200 people.

The Britain-based Syrian Observatory for Human Rights said one person was killed in Nawa, in the southern Daraa province where the protest movement began on March 15 and two others in the eastern oil hub of Deir Ezzor.