LUXEMBOURG - The European Union accused Russia on Monday of putting peace efforts at risk in Syria, calling on Moscow to stop bombing Western-backed rebels but failing to agree on a role for President Bashar al-Assad in resolving the crisis.

Seeking a common front in their criticism of Russia’s dramatic military intervention, EU foreign ministers warned that air strikes designed to support Assad could also deepen the 4-1/2-year civil war that has killed 250,000 people.

“The recent Russian military attacks ... are of deep concern and must cease immediately,” ministers said in their most strongly-worded statement on Russia’s intervention. “The military escalation risks prolonging the conflict, undermining a political process, aggravating the humanitarian situation and increasing radicalisation,” said the ministers, who are meeting in Luxembourg. EU leaders are also expected to criticise Russia at a summit in Brussels on Thursday, EU officials say.

After years of inaction in Syria, the EU is now desperate to stem the flow of migrants into Europe. Its stark criticism of Moscow underscores just how far diplomatic efforts have faltered since a UN meeting in New York in late September, when Europe and the United States looked to Russia for help.

Russian incursions into Turkish airspace and air strikes directed not at Islamic State militants but at relatively moderate opposition groups have alienated the West, while leaving EU and U.N diplomacy in disarray, diplomats said.

Plans have evaporated for a ‘contact group’ working with Russia, the United States, Iran and Saudi Arabia to find a post-conflict settlement, while EU diplomats have few ideas about how to find a political solution.

“All Assad’s main opponents are dead, in jail or in exile. And nobody wants another Libya,” said one EU diplomat involved in the discussions, referring to Libya’s collapse after its veteran leader Muammar Gaddafi was ousted.

The EU’s own position on Assad remains unclear, with no agreement on whether he could play a role in agreeing a ceasefire and paving the way for elections, or whether the president should go into exile or immediately to prison. The EU’s foreign policy chief Federica Mogherini suggested that contact with Assad should be made through the United Nations, but Spain’s foreign minister reiterated Madrid’s view that the West will need to negotiate with Assad to stabilise Syria. “Negotiations are done between enemies,” Jose Manuel Garcia-Margallo told reporters. France, which is investigating Assad for war crimes, insisted that the Syrian leader could only be involved in the transition in a symbolic way, and that it must be clear at the start of any negotiation that he would not be there at the end.

“For peace in Syria, we need a political transition. That must be done without Assad,” said France’s European affairs minister Harlem Desir.

Britain says Assad cannot be allowed to remain as president but is willing to discuss how and when he might leave.

Meanwhile, Syrian troops aided by Russian air strikes fought their fiercest clashes with rebels in weeks on Monday.

On the ground in Syria, the army command said regime forces had captured Kafr Nabuda village in central Hama province, extending their advance in the region around the strategic Damascus-Aleppo highway.

Regime forces have been pushing an offensive on both sides of the highway towards the town of Khan Sheikhun, just over the provincial border in Idlib.

The Syrian Observatory for Human Rights monitor said clashes were ongoing in Kafr Nabuda, adding that Russian warplanes had carried out at least 20 strikes in and around the village. “The clashes are the fiercest since the Russian air campaign began on September 30,” Observatory chief Rami Abdel Rahman said.

Many of Russia’s air strikes so far have been focused on the area where Hama, Idlib and Latakia provinces meet. Latakia province on the Mediterranean coast is a stronghold of the regime and the home of Assad’s ancestral village.

Idlib province is controlled by the powerful Army of Conquest rebel alliance which includes Al-Qaeda affiliate Al-Nusra Front.

In recent months, the alliance has sought to expand from Idlib into Hama and the strategic Sahl al-Ghab plain between the three provinces in a bid to target Latakia.

Abdel Rahman said the rebels were sending reinforcements to Kafr Nabuda to battle the regime, which was also shelling other parts of Hama and Latakia provinces.

Syria’s army command also reported advances in northern Latakia province and said regime forces had taken control of the “duty free zone” outside Aleppo city in the north.

The city is divided between rebel control in the east and government control in the west, while the situation is largely the reverse in the countryside around Aleppo.

A military source said the advance by regime forces would help protect territory it holds in the area, including the Sheikh Najjar industrial area to the city’s northeast.