Rebel troops hit offices of Syria's ruling party on Thursday, a day after a daring raid on an intelligence base that prompted Russia to warn that its longtime ally risks "full-scale civil war."
The rocket-propelled grenade attack in northwestern Idlib province, near Turkey, came as government forces killed eight people, including two children, despite an Arab League ultimatum that Syria halt the bloodshed or risk sanctions.
"A group of dissident troops attacked regime youth offices, where security agents were meeting, with rocket-propelled grenades and clashes broke out," said the Britain-based Syrian Observatory for Human Rights.
The official Sana news agency denied the attack had taken place, saying it was "misinformation by the media."
On Wednesday fighters opposed to Syria's President Bashar al-Assad raided an intelligence base outside the capital, reports of which prompted Russian Foreign Minister Sergei Lavrov to warn both sides to stop the violence.
"Of course, if the opposition is going to use such methods it will lead... to full-scale civil war," Lavrov said.
The minister was speaking after talks with EU foreign policy chief Catherine Ashton, who said "it's time for President Assad to stand down."
Ashton also invited Arab League chief Nabil al-Arabi to meet with EU foreign ministers in the near future to discuss ways to pile pressure on Syria's regime.
France, a major instigator of NATO's military intervention in Libya, continued its own diplomatic push against Damascus with Foreign Minister Alain Juppe in Turkey for talks on the first stop of a tour that will continue on to Arab League heavyweights United Arab Emirates, Saudi Arabia, Qatar and Kuwait.
Russia has been deeply opposed to Western efforts to internationalise the crisis, fearing it might clear the way for a Libya-style Western military intervention under a UN mandate.
On October 4, it joined with China in vetoing a Western-drafted Security Council resolution that would have threatened Assad's regime with "targeted measures" if it continued its deadly crackdown on protesters, which the UN says has killed more than 3,500 people.
Leading Syrian dissident Haithem al-Maleh took issue with Russia's warning of civil war, saying the intelligence base, where a number of detainees were being held, was a legitimate target in the protection of civilians.
"This attack on one of the worst departments of the security services does not mean a civil war. This army of defectors is protecting civilians, no more, no less," Maleh told Al-Jazeera television.
In New York, European nations said they have key Arab support for a UN General Assembly resolution condemning human rights abuses by Syria's regime, whose success could increase pressure for the Security Council to act.
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"The Arab world has sent a very clear message: the massive human rights violations and the suffering of the Syrian people have to stop," said German Ambassador Peter Wittig.
But Wittig said it was still imperative for the UN Security Council to condemn Assad and heed "the strong voices from the region".
On the ground, security forces killed a nine-year-old girl and a man in the eastern oil hub of Deir Ezzor, the Observatory said.
Two civilians were killed in the central city of Homs and another four, including a young boy, in Idlib, the watchdog added.
The deaths came after at least 23 people were killed on Wednesday, even as Arab League foreign ministers, who had suspended Syria at the weekend, met in Morocco and gave Damascus three days to halt the bloodshed or risk sanctions.
A League diplomat in Rabat told AFP "Syria's suspension came into effect yesterday (Wednesday) but that is not to say that the League is going to sever its contacts with the Syrian government."
Ankara, a onetime Assad ally that has become one of its most outspoken critics, joined the Morocco meetings.
Turkish Prime Minister Recep Tayyip Erdogan stepped up the rhetoric on Thursday, saying more would be heard from the international community if Syria had rich oil resources like Libya.
"The silence and unresponsiveness of those who have an appetite for Libya to the massacres in Syria is creating irreparable wounds in the conscience of humanity," he charged.
In Istanbul, the leader of Syria's exiled Muslim Brotherhood said his compatriots would accept Turkish "intervention" in the conflict.
"The Syrian people would accept intervention coming from Turkey, rather than from the West, if its goal was to protect the people," Mohammad Riad Shakfa told a news conference.
On Thursday, Turkish pro-government daily Sabah reported the opposition Syrian National Council, together with the Brotherhood, had asked Turkey to establish a Libya-style no-fly zone in areas of northern Syria where there have been deadly clashes between troops and fugitive dissidents.
In a sign of Damascus's fast-growing isolation, Beijing, which joined Moscow in vetoing the October draft Security Council resolution, said Thursday it was "highly concerned" by developments and called on the Assad regime to cooperate with the Arab League.