BEIRUT (AP) -- Syrian security forces opened fire Friday on protesters calling for the overthrow of President Bashar Assad, killing at least seven, activists said.
The killings came as the U.N.'s top human rights official urged the international community to take "immediate measures" to protect civilians in Syria.
The protests were called to support the Free Syrian Army, a group of army defectors who have reportedly clashed with loyalists in northern and central Syria. The demonstrations were the most explicit show of support offered so far by the country's protest movement to the group, whose operations have led to an increased militarization of the seven-month-old uprising.
Clashes between troops and gunmen believed to be defectors left at least 25 people dead on Thursday, according to the London-based Syrian Observatory for Human Rights.
Syria-based activist Mustafa Osso and the Local Coordination Committees, an activist group, said the protests on Friday spread from the suburbs of the capital Damascus to the southern province of Daraa, the northern provinces of Aleppo, Idlib and Hassakeh, and to the central regions of Homs and Hama, as well as to other areas.
The observatory and the LCC said security forces killed one protester in the Damascus suburb of Saqba and another in the village of Andan in the northern province of Idlib.
The two groups had different death tolls from the southern village of Dael, with the observatory reporting seven people killed and the LCC reporting five dead. It was impossible to resolve the discrepancy or to independently verify the reports.
A banner in English carried by protesters in the northern village of Kfar Nabul urged the United States to overthrow the Syrian president. "Americans!... If you don't topple Al-Assad now don't boast about democracy again," said the banner, a photo of which appeared on the LCC's Facebook page.
The uprising against Assad's regime began in mid-March amid a wave of anti-government protests in the Arab world that toppled autocrats in Tunisia, Egypt and Libya.
In Geneva, Navi Pillay, the U.N. High Commissioner for Human Rights, warned that an unrelenting crackdown by Assad's government could worsen unless further action is taken. She said the death toll from seven months of anti-government unrest in the country rose to above 3,000.
"The onus is on all members of the international community to take protective action in a collective and decisive manner, before the continual ruthless repression and killings drive the country into a full-blown civil war," Pillay said in a statement.
She didn't elaborate on what measures the international community could take beyond the sanctions already imposed on Assad's regime.
Her spokesman, Rupert Colville, told reporters in Geneva that it was up to the U.N. Security Council to decide what action was appropriate.
But he added: "What has been done so far is not producing results and people continue to be killed every single day."
"Just hoping things will get better isn't good enough, clearly," Colville said.
The U.N. human rights office estimates that more than 3,000 people have now been killed since mid-March - about 10 to 15 people every day. The figure includes at least 187 children. More than 100 people had been killed in the last 10 days alone, the global body said.
Colville said hundreds more protesters have been arrested, detained, tortured and disappeared. Families of anti-government protesters inside and outside the country have also been targeted for harassment.
Jordans reported from Geneva.
Bassem Mroue can be reached on http://twitter.com/bmroue