A ceasefire has reportedly been agreed between Asef Shawkat, Syria's deputy defence minister, and town leaders in Zabadani, near the capital, Damascus.
Opposition figure Kamal Labwani, who fled to Jordan two weeks ago, told Al Jazeera on Wednesday that an agreement had been made between representatives of the town and Shawkat, who is the brother-in-law of President Bashar al-Assad.
Labwani said town leaders had consulted the opposition Free Syrian Army and local activists, who in turn agreed to the ceasefire.
Under the deal, troops and tanks were to withdraw from Zabadani, a town of about 40,000 people on the border with Lebanon, and opposition fighters would withdraw from the streets, according to Labwani.
There was no comment from the Syrian authorities.
"As of now there is no shelling and no gunfire. It is quiet. But the army is still surrounding the area," a Zabadani
resident who gave her name as Rita told the Reuters news agency. "The agreement last evening was that the army would withdraw and the armed rebels would leave the streets and clear roadblocks."
Zabadani, located about 30km northwest of Damascus, in the foothills of the mountains which separate Lebanon from Syria, has seen regular big demonstrations demanding the removal of Assad.
Troops backed by tanks reportedly attacked the town on Friday, in the biggest military offensive since Arab League
monitors went into the country last month.
A statement by activists from Zabadani, published on Facebook, said the ceasefire was agreed after two days of negotiations.
Security Council split
International pressure is mounting on Syria to end its crackdown on dissidents, and parts of the opposition are calling for foreign intervention.
However, Russia's foreign minister said on Wednesday his country would block any attempt by Western nations to secure United Nations support for the use of force against Syria.
"If some intend to use force at all cost ... we can hardly prevent that from happening," Sergei Lavrov said. "But let them do it at their own initiative on their own conscience, they won't get any authorisation from the UN Security Council".
In-depth coverage of escalating violence across Syria
His comments came a day after Security Council diplomats held prolonged talks on a proposed Russian resolution on Syria. Lavrov said the draft was aimed at making it explicitly clear that nothing could justify a foreign military interference.
Western diplomats said the draft fell short of their demand for strong condemnation of violence against civilians, that the UN estimates has left more than 5,000 people dead.
The Security Council has been unable to agree on a resolution since the unrest began in March because of strong opposition from Russia and China.
Beijing on Wednesday defended the Arab League's widely criticised observer mission in Syria, which was deployed last month.
"Since the Arab League observer mission began, the violence in Syria has not completely ended, but the security situation of major areas has improved, which shows the mission is effective," foreign ministry spokesman Liu Weimin said.
British Prime Minister David Cameron on Wednesday accused Iran and Lebanon's Hezbollah movement of helping to prop up Assad, whom he described as "a wretched tyrant".
"Britain needs to lead the way in making sure we tighten the sanctions, the travel bans, the asset freezes, on Syria," Cameron told parliament in London.
European Union foreign ministers are expected to discuss extra EU sanctions at a meeting on Monday.
Hundreds of killings on both sides have been reported since the Arab League sent observers last month to see whether Damascus was respecting a peace plan it accepted on November 2.
An Arab League source said Damascus would accept a one-month extension of the monitoring mission, but no broadening of its mandate.
The Local Co-ordinating Committees, an opposition activist network, said 22 people were killed on Wednesday, eight of whom were said to be defectors from the army.
The activists said 13 of the deaths occurred in Homs province.
Syria's state news agency SANA said the strangled body of a veterinarian doctor was found in Homs bearing marks of torture four days after he was kidnapped by an "armed terrorist group".