Syrians were called upon to vote on a new constitution on Sunday, in the face of opposition calls for a boycott of the poll.

Voting in the referendum, held against the backdrop of deadly violence, began at 7 a.m. local time and was due to continue for 12 hours.

Some 14.6 million eligible voters are being asked whether or not they agree to the terms of a new constitution. Advocates of the reform say it will create a multi-party democracy and bring the dominance of the ruling Baath Party - in power since 1963 - to an end.

However, the two main umbrella opposition groups, the Syrian National Council and the National Coordination Body for Democratic Change, have called for a boycott of the poll describing it as being "stained with blood" and compromised.

Strong criticism

The referendum was also strongly criticized internationally. "The referendum in Syria is nothing more than a farce," German Foreign Minister Guido Westerwelle said. "Sham votes cannot be a contribution to a resolution of the crisis. Assad must finally end the violence and clear the way for a political transition."

US Secretary of State Hillary Clinton said there was "every possibility" that Syria would descend into civil war. She encouraged Syrians to rise up against the regime.

"We are appealing to the members of the Syrian army to put their country first,"

Voter turnout was reported to be low in the Damascus districts of Rukneddine and Barzeh, both of which have seen unrest in recent months. Syria's Information Ministry had taken international journalists to the neighborhoods to report on the vote.

State television reported that "large number of voters" had turned out.

Further bloodshed, evacuation talks

Syrian regime forces killed 16 civilians across the country on Sunday, nine of whom died in the besieged city of Homs, the British-based Syrian Observatory for Human Rights said. It added that 10 government soldiers had also died in the fighting.

The International Committee of the Red Cross (ICRC) said Sunday it had resumed negotiations to allow the evacuation of Homs' artillery-battered Baba Amr district. Nearly 12 hours of talks on Saturday had proved unsuccessful.

The annual session of the UN Human Rights Council was set to open on Monday with efforts to put more pressure on the Syrian regime on the agenda. The meeting comes after a list of Syrian officials suspected of crimes against humanity was handed to the council by international investigators.

The UN-commissioned panel said a widespread and systematic pattern of gross violations by Syrian forces, "in conditions of impunity," had been documented since the uprising began last March.

rc, ng/pfd (AP, AFP, Reuters)