Five EU nations have summoned Syrian ambassadors to condemn Damascus’ recent violent crackdown on anti-government protesters, France has said.
Paris said the diplomatic action had been carried out jointly by France, Britain, Germany, Italy and Spain.
Earlier, UN chief Ban Ki-moon condemned Syria for using tanks and live ammunition against the demonstrators.
There are reports of further shooting in the southern city of Deraa, where the rallies first erupted last month.
More tanks are said to be headed for city – where army troops attacked protesters on Monday.
More than 450 people across Syria have allegedly been killed since the pro-democracy protests began nearly six weeks ago.
The government of President Bashar al-Assad disputes the Western view that the demonstrations have been non-violent.
In a statement carried by the official news agency, it said it had sent troops to several cities on the request of citizens who were worried about “armed extremists”. Opposition leaders say the protests are peaceful.
‘Snipers’ in Deraa
Senior French diplomat Herve Ladsous met Syrian ambassador Lamia Chakkour on Wednesday, the French foreign ministry said.
It said that Paris expressed “firm condemnation of the escalation of the repression by Syrian authorities against the population”.
The communication was “part of a co-ordinated move with Britain, Germany, Spain and Italy”.
EU envoys are also due to meet in Brussels on Friday to discuss imposing sanctions on Syria.
Meanwhile, in Deraa, sources reported sporadic shooting and explosions on Wednesday.
Footage posted on the internet appeared to show Syrian tanks heading towards the city to reinforce troops who moved into it two days ago.
Amnesty International quoted eyewitnesses as saying army snipers were shooting at wounded residents lying in the streets and that other people were trying to save them.
But with communications apparently cut off from Deraa, it is hard to be sure what is happening there, the BBC’s Jim Muir in neighbouring Lebanon says.
Elite army units were also said to have moved into Douma, a suburb of Damascus, our correspondent adds.
He adds that there are also reports of widespread arrests of opposition figures around the country.
Despite the crackdown, protest organisers have called for sit-ins on Thursday to commemorate those who have been killed. Friday – the traditional day of protests – had been designated as a “day of rage”.
The death toll has now risen to 453 since the start of the unrest, the Syrian Observatory for Human Rights says.
‘Refusal to fire’
On Wednesday, a human rights activist said he had documented the case of a soldier being shot by the army for refusing to fire on protesters in Baniyas.
The army blamed radical Islamists for his death, but mourners at the soldier’s funeral “openly accused the security forces of shooting that soldier”, Wissam Tarif, director of the Syrian human rights organisation Insan, told the BBC.
The 15-nation UN Security Council is expected to take up the issue of Syria again later on Wednesday.
A draft text – proposed by the UK, France, Germany and Portugal – condemns the violence against civilians and backs Mr Ban’s call for a “transparent” independent investigation into deaths in the protests.
The Syrian envoy to the UN, Bashar Jaafari, said Damascus was capable of carrying out its own inquiry and had “nothing to hide”.
The BBC’s Barbara Plett, at the UN headquarters in New York, says that it will be difficult for Security Council members to reach agreement.
Veto-holders China and Russia are especially cautious as they are unhappy about intervention in Libya, she says. BBC