Syria referendum goes ahead amid military onslaugh.

At least 31 Syrian civilians and soldiers were killed on Sunday in bloodshed that coincided with a vote on a new constitution that could keep President Bashar al-Assad in power until 2028.

Assad's opponents see the referendum as a sick joke given Syria's turmoil. The Syrian Observatory for Human Rights said a military bombardment of opposition districts in Homs had killed nine civilians while rebels had killed four soldiers in clashes.

The British-based Observatory said eight civilians and 10 members of the security forces were killed in violence elsewhere in Syria, scene of what has become an increasingly militarised revolt against four decades of Assad family rule.

Voting took place in the referendum on a new constitution, which Assad says will lead to a multi-party parliamentary election in three months. The result is expected to be announced on Monday. Western powers described the vote as a sham.

"What should we be voting for, whether to die by bombardment or by bullets? This is the only choice we have," said Waleed Fares, an activist in the Khalidiyah district of Homs, where bombardment is now in its fourth week.

"We have been trapped in our houses for 23 days. We cannot go out, except into some alleys. Markets, schools and government buildings are closed, and there is very little movement on the streets because of snipers," he said.

He said another besieged and battered district, Baba Amro, had had no food or water for three days. "Homs in general has no electricity for 18 hours a day." Tight curbs on independent reporting in Syria make witness reports hard to verify.

The Interior Ministry acknowledged obliquely that security conditions had disrupted voting, saying: "The referendum on a new constitution is taking place in a normal way in most provinces so far, with a large turnout, except in some areas."

The Syrian government, backed by Russia, China and Iran, and undeterred by Western and Arab pressure to halt the carnage, says it is fighting foreign-backed "armed terrorist groups".