Paris (AFP) - French President Francois Hollande said Saturday that EU leaders meeting in Brussels were likely to boost sanctions on Russia over the escalating Ukraine conflict.

"Sanctions will be no doubt increased and the (European) Commission will have to work on" implementing this, Hollande told reporters after a meeting of centre-left leaders in Paris.

The Ukraine crisis is "the biggest crisis since the end of the Cold War," said Hollande.

"It's close to Europe. It's on the border of Europe... What is happening concerns Europe directly. Not just Europe, the whole world, but especially Europe," he added.

Unlike other world leaders, Hollande stopped short of confirming the presence of Russian troops on Ukrainian soil, saying it was "probable" there were Russian soldiers there and definitely "armed rebels helped by Russia".

However, he said recent events were a "definite escalation" with "2,500 dead in the last few weeks."

"Europe has to act. It already has. But in the face of this escalation in tension, there are new decisions to be taken," he said.

The European Union and the United States in July stepped up sanctions against Russia and pro-Moscow separatists in Ukraine after a Malaysia Airlines passenger jet was shot down over rebel-held territory.

Hollande said Ukrainian President Petro Poroshenko would be "very closely listened to" at Saturday's summit of EU leaders.

He said he had called Russian President Vladimir Putin on Friday to insist on the importance of Ukrainian sovereignty and to stress that continuing to arm separatists would fuel the crisis further.

He reiterated the willingness of France to hold talks in the so-called "Normandy format", bringing together Russia, Ukraine, Germany and France, but there were "pre-conditions" for such negotiations to go ahead.

"There's no time to lose," he said, warning there was a "risk of a genuine war".

Earlier on Saturday, EU foreign policy chief Catherine Ashton said EU leaders would make a decision on further sanctions on Russia, expressing "deep concern" over the situation.

Speaking after a meeting of EU foreign ministers in Milan, she said the officials were "very clear that there is no military solution".

"We need a sustainable political solution that respects Ukraine's territorial integrity and sovereignty," Ashton told reporters.

EU leaders meet later on Saturday in Brussels for a summit that was supposed to be about doling out top jobs in the bloc but has been taken over by events on the EU's eastern edge.