Syrian forces opened fire at funerals for slain political protesters, a human rights activist said Sunday, leaving two more people dead as Syria tries to subdue weeks of demonstrations against President Bashar Assad.

The two were killed Saturday in al-Kaswa, a suburb of the Syrian capital, Damascus, said Rami Abdul-Rahman, the London-based director of the Syrian Observatory for Human Rights. Security forces opened fire when the funerals for protesters killed on Friday turned into protests themselves, he said.

Footage posted online by activists showed dozens of people in a Saturday funeral procession for three of the dead in al-Kaswa, shouting "Allahu Akbar!" or "God is great!" and "Bashar, get out!"

One person was also killed Saturday in Damascus' Barzeh neighbourhood and two were killed in the village of al-Quseir, near the Lebanese border, Abdul-Rahman said.

Hundreds of Syrians, some with gunshot wounds, crossed into neighbouring Lebanon over the weekend fleeing the crackdown. The new arrivals joined thousands of other Syrians who fled to Lebanon in May and early June.

The military's recent sweep through northwestern Syria, where armed resistance flared in early June, also has sent more than 11,700 refugees fleeing across the border to refugee camps in Turkey.

Syrian activists said 20 people were killed in Friday demonstrations across Syria, including two children aged 12 and 13.

The opposition says some 1,400 people have been killed in recent months as the government has cracked down on the movement demanding an end to four decades of autocratic Assad family rule.

Syria's military spokesman, meanwhile, said in a CNN television interview that 1,300 members of security forces have been killed in the months-long unrest, during which the government has repeatedly said its forces have been attacked by "armed gangs."