France urged nations to send a "powerful signal" to Syria, after accusing Damascus of "crimes against humanity," as activists said regime forces killed at least 23 people, 21 of them in a tank-backed raid on the flashpoint central city of Homs.
"The Syrian regime has committed crimes against humanity," French Foreign Minister Alain Juppe said during talks in Moscow with his Russian counterpart Sergei Lavrov.
"The way it (the Syrian regime) suppressed the popular protests is unacceptable," he said Wednesday, expressing hope that Russia would change its stance and back UN condemnation of the crackdown.
The Syrian authorities, he said, should be sent "a powerful signal that such actions cannot continue."
But Lavrov gave no signs of being ready to ease a Russian position that last week saw Moscow lash the European Union for imposing a crippling oil embargo on Syria.
"We are convinced that the essential thing is to start dialogue at the talks table," Lavrov said.
"We consider that inciting certain forces within the opposition to boycott the invitation to dialogue is a dangerous path and risks a repetition of the Libyan scenario, which neither Russia nor France wants."
Russia has staunchly opposed attempts by Western governments to push through a UN Security Council resolution targeting President Bashar al-Assad and has circulated an alternative draft calling for him to implement reforms.
European Union nations are considering fresh sanctions against Syria, a diplomatic source who asked not to be identified said in Brussels.
"There is preliminary political agreement" between EU nations on slapping a ban on oil-sector related investment as part of a seventh round of sanctions against the Assad regime, the source said.
Meanwhile, the US ambassador to Damascus, Robert Ford, said in a posting on Facebook that Assad's regime "bears the responsibility for the violence."
The United Nations says 2,200 people have been killed since democracy protests flared in Syria in mid-March.
Activists said the Syrian security forces killed at least 23 more people on Wednesday.
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The Britain-based Syrian Observatory for Human Rights said they included 21 people in Homs and two in Sarmeen, in Idlib province in the northwest.
The Local Coordination Committees, which organise the anti-regime protests on the ground, said security forces also killed one person in the central city of Hama.
In Homs, security forces used "gunfire and stun grenades to terrorise the people near the police headquarters around the citadel," the LCC said in a statement sent to AFP in Nicosia.
The activists said forces backed by tanks swept early morning into Homs, where communications and Internet services were cut in many neighbourhoods.
The Syrian Observatory said "military reinforcements including 20 truckloads of soldiers entered the city," and that there was "intense gunfire in the market and governorate headquarters."
Eight soldiers and five "insurgents" were killed in Homs, the official Sana news agency reported, adding that "dozens" of soldiers were wounded by "armed terrorists who attacked civilians and security forces" across the city.
"Security forces succeeded in eliminating them and five of the armed criminals were killed," Sana said, adding that several arrests had been made.
It said there was an "anti-tank missile strike against the hospital in Homs," and another near Homs where an armed group ambushed and attacked a military truck.
The deadly crackdown came only hours after Syria said it was postponing a planned visit to Damascus by the head of the Arab League.
The Cairo-based pan-Arab organisation said Nabil al-Arabi would now visit on Saturday.
Damascus had postponed the trip at the 11th-hour "due to circumstances beyond our control."
Arabi has been commissioned by the 22-member bloc to travel to Damascus with a 13-point document outlining proposals to end the bloody crackdown on dissent and push Syria to launch reforms.
According to a copy of the document seen by AFP, Arabi is to propose that Assad hold elections in three years, move towards a pluralistic government and immediately halt the crackdown.
The initiative, agreed by Arab foreign ministers last month, angered Syria which said it contained "unacceptable and biased language."
Syria's regime, which has promised to launch a wide range of reforms to appease protesters, blames the unrest on foreign-backed "armed terrorist gangs."