Syrian security forces have opened fire on protesters in several parts of the country, killing at least six people.

Activists say anti-government demonstrators were killed on Friday after Syrian forces used live ammunition on opposition rallies in areas that include Damascus suburbs.

The crackdown on dissent occurred the same day that U.N. human rights officials said the death toll from seven months of anti-government protests in Syria had topped 3,000.

U.N. High Commissioner for Human Rights Navi Pillay warned that Syria's violent repression of dissent could drive the country into full-blown civil war. She added that about 100 people had died in the past 10 days.

On Thursday, activists said clashes between security forces and armed men who were believed to be army defectors left at least 19 people dead.

They say some of the violence took place in the northern Idlib province, where security forces battled army deserters and gunmen.

Syria has used military force to crush months of opposition protests calling for the ouster of Syrian President Bashar al-Assad. The crackdown has led to international condemnation of Syria that includes a European Union decision, on Thursday, to impose sanctions on Syria's biggest state bank.

President Assad's government has blamed much of the deadly violence on “armed gunmen” and “terrorists.”