Last Updated 2:32 p.m. ET
BEIRUT - Syrian rebels repelled a push Monday by government tanks into a central town held by forces fighting President Bashar Assad's regime in an 11-month conflict that looks increasingly like a civil war.
The military pressed its offensive on Rastan a day after the regime rejected Arab League calls for the U.N. to create a peacekeeping force in Syria and for an end to the violent crackdown on dissent. Damascus called the League initiative "a flagrant interference in (Syria's) internal affairs and an infringement upon national sovereignty."
With diplomatic efforts bogged down, the conflict is taking on the dimensions of a civil war, with army defectors clashing almost daily with soldiers. The rebels have taken control of small swathes of territory in central Homs province, where Rastan is located, and the northwestern province of Idlib, which borders Turkey.
The Britain-based activist group Syrian Observatory for Human Rights said at least three government soldiers were killed in the regime attempt to storm Rastan, which has been held by the rebels since late January.
"Troops maneuvered by moving on the northern edge of town, then other forces attacked from the south," said Rami Abdul-Rahman, who heads the Observatory. He said hundreds of army defectors were in control of Rastan.
Rastan, home to some 50,000 people, was one of the first areas in Syria where people took up arms to fight the regime.
The uprising began last March as mostly peaceful protests against Assad's authoritarian rule, but has become more militarized in the face of the brutal military crackdown.
The U.N. human rights chief, Navi Pillay, told the General Assembly on Monday that more than 5,400 people were killed last year alone, and the number of dead and injured continues to rise daily. She said the scale of abuses by the Syrian government indicate that crimes against humanity have taken place since March and are continuing.
Rastan was taken by defectors twice in the past only to be retaken by Syrian troops. Calls to residents did not go through on Monday and the telephone lines appeared to be cut, as they usually are during military operations.
The Observatory, which has activists around Syria, said government forces also bombed the rebel-held Homs neighborhood of Baba Amr, which has been under siege for more than a week. It reported clashes in the village of Busra al-Harir in the southern province of Daraa between troops and army defectors.
In the central city of Hama, a sniper shot dead a civilian, the group said. In Idlib, the Observatory said 45 vehicles, including tanks, arrived in the town of Jisr al-Shughour.
Assad's bloody crackdown on the opposition has left Syria almost completely isolated internationally, except for one key ally Russia. China and Russia outraged the U.S. and many Arab countries earlier this month when they delivered a double veto to block a U.N. Security resolution calling on Assad to leave power.
The 22-nation Arab League has been at the forefront of regional efforts to end the crisis. The group put forward a plan that Assad agreed to in December, then sent in monitors to check whether he was complying. When it became clear the regime was flouting the terms of the agreement and the killings were continuing, the League pulled out the observers last month.
On Sunday, the League called for the Security Council to create a joint Arab-U.N. peacekeeping force for Syria and urged Arab states to sever all diplomatic contact with Damascus.
The group said it wanted to provide Syrian opposition groups with political and material support, and urged the opposition to unite ahead of a Feb. 24 meeting in Tunisia of the "Friends of Syria" group, which includes the United States, its European allies and Arab nations working to end the uprising against Assad's authoritarian rule.
Britain's Foreign Secretary William Hague said Britain would discuss the possibility of a joint African Union-U.N. peacekeeping force for Syria ahead of the Tunisia talks.
"Such a mission could have an important role to play in saving lives," he said.
In Moscow, Russian Foreign Minister Sergey Lavrov said there must be a cease-fire in Syria before any peacekeeping mission could be sent to the country, rejecting calls for a joint Arab-U.N. force as premature.
Lavrov told reporters in Moscow that his country will study the Arab League proposal for a joint peacekeeping mission in Syria with the United Nations.
"We should first have peace, which would be supported," Lavrov said at a news conference in Moscow with United Arab Emirates Foreign Minister Sheik Abdullah bin Zayed Al Nahyan.
Chinese Foreign Ministry spokesman Liu Weimin refused to directly answer questions about whether Beijing would support the League's call, saying only that China backs the League's "political mediation efforts."
He reiterated China's stance that it wanted to see Syrian authorities and opposition forces "properly solve their disputes through dialogue."
Assad's regime has long blamed terrorists for the revolt that began with peaceful calls for democratic change, but is morphing into a bloody, armed insurgency.