There was no let-up in the violence as Syrians went to the polls to cast their ballots on a new constitution on Sunday.

At least 31 people are reported to have died in the bloodshed on Sunday alone.

Nine civilians died as a result of Syrian army shelling in mainly opposition districts in the central city of Homs, according to the Syrian Observatory for Human Rights. Rebels from the self-styled Free Syria Army killed four government soldiers in fighting in the city. Eight civilians and 10 members of the military died in other parts of the country, the London-based Observatory said.

Polls kept open late

Voting in the referendum began at 7 a.m. local time and had been scheduled to close 12 hours later. However, officials said the polls had been kept open for an extra three hours in some areas in order to allow people who hadn't already done so to cast their ballots.

Syrian President Bashar al-Assad said if approved, the new constitution would lead to a multi-party parliamentary election within three months and end almost five decades of domination by his ruling Baath Party.

However, Syria's 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 and for soldiers not to fire upon civilians.

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

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.

Evacuation talks

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.

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