Syrian forces killed 11 civilians and wounded 28 others on Monday (February 27th) after more than 150 people were killed in violence over the weekend, AFP reported the Syrian Observatory for Human Rights as saying.

At least 65 people were killed in Syria Sunday (February 26th) on a day when some Syrians voted in a referendum on a new draft constitution, the Syrian Revolution General Commission said.

The commission said most of the victims, including five children, were killed in Homs and Hama.

Syrian Interior Minister Mohammed al-Shaar told a press conference on Monday that turnout for the referendum reached 57.4 percent of eligible voters, with 89.4 percent of the 8.376 million who cast their ballots in Sunday's referendum saying "yes" to the new constitution.

The Syrian opposition called for a boycott of the referendum, according to AFP.

The United Nations doubts the credibility of the constitutional referendum held in Syria amid "pervasive violence," a UN spokesman said Monday.

Any vote in Syria must be held "in conditions free of violence and intimidation," UN deputy spokesman Eduardo del Buey told reporters, adding that UN Secretary General Ban Ki-moon had just "noted" Sunday's vote organized by President Bashar al-Assad's government.

Meanwhile, the Syrian Network for Human Rights said the 24-hour bombardment of Homs has continued to target the Baba Amr district, where most of this city's victims were killed yesterday.

Syria's state-run news agency (SANA) said that "40 armed gunmen have voluntarily turned themselves in, together with their weapons, to the Syrian forces in Bab Amr district."

The news agency said the "the terrorist group elements were forced to surrender after the Syrian army succeeded in opening areas that were previously controlled by those armed groups."