• Ukrainian leader Poroshenko seeks help against Russia

• Poland’s Tusk, Italian Mogherini appointed Council President and Foreign Policy Chief

• France warns no time to waste to halt slide into war

EU leaders will threaten Russia with new sanctions over Ukraine but, fearful of a new Cold War and self-inflicted harm to their own economies, should give Moscow another chance to make peace.

At a summit in Brussels yesterday, EU leaders chose Polish Prime Minister Donald Tusk as the new President of their Council and Italian Foreign Minister Federica Mogherini as the bloc’s new foreign policy chief, replacing Briton Catherine Ashton, outgoing council president Herman Van Rompuy said on social media site Twitter.

EU officials gave Ukraine’s embattled President Petro Poroshenko a warm welcome and assurances of further economic and other support.

But divisions among the 28 EU nations have hampered action against Moscow, and a draft of yesterday’s final statement indicates that they will merely ask the bloc’s executive arm “urgently” to prepare more options for sanctions.

French President François Hollande stressed that a failure by Russia to reverse a flow of weapons and troops into eastern Ukraine would force the bloc to impose new economic measures.

“Are we going to let the situation worsen, until it leads to war?” Hollande said at a news conference. “Because that’s the risk today. There is no time to waste.”

British Prime Minister David Cameron said: “We have to address the completely unacceptable situation of having Russian troops on Ukrainian soil. Countries in Europe shouldn’t need to think long before realising just how unacceptable that is. We know that from our history.

Lithuanian President Dalia Grybauskaite said Russia is at war with Ukraine and so effectively at war with Europe

“So consequences must follow if that situation continues.”

The President of formerly Soviet Lithuania, an outspoken critic of Vladimir Putin and of EU hesitation to challenge him, called for urgent military supplies to Kiev and a tougher arms embargo on Russia. Dalia Grybauskaite said Moscow, by attacking Ukraine, was effectively “in a state of war against Europe”.

But large Western countries are wary of damaging their own economies through sanctions. Those include Germany, Britain and France, as well as Italy, which is heavily dependent on Russian gas.

Poroshenko gave short shrift to Moscow’s denials by denouncing the past week’s incursion of thousands of troops with hundreds of armoured vehicles and said he expected the summit to order the European Commission to prepare a new set of sanctions. But, like Commission President José Manuel Barroso, he used their joint news conference to stress a will to find a political solution to a crisis that President Putin blames on Kiev’s drive to turn the ex-Soviet state away from its former master Moscow and toward a Western alliance with the EU and Nato.

He said he was not looking for foreign military intervention and expected progress toward peace as early as Monday – because failure could push the conflict to a point of no return: “Let’s not try to spark the new flame of war in Europe,” he said.

Barroso also warned of the risk of a “point of no return” in stressing that EU leaders wanted to defuse the confrontation with their nuclear-armed neighbour.

“It makes no sense to have... a new Cold War,” Barroso said. Further conflict would hurt all of Europe, he said, adding that sanctions were meant to push Moscow to talk. His Commission already had prepared a number of options for further measures.

Diplomats said Polish Prime Minister Donald Tusk had broad support for Van Rompuy’s job, eclipsing the former frontrunner, Danish Social Democrat Prime Minister Helle Thorning-Schmidt.

Many officials in Brussels expect a deal that will balance the interests of left- and right-wing factions across the bloc, eastern and western states, northern Europe and the south, as well as satisfy pressure for more women in senior EU roles.

In overall charge of the executive Commission, in succession to Barroso, will be conservative former Luxembourg premier Jean-Claude Juncker, appointed at a stormy summit two months ago.

Eastern leaders, alarmed by a resurgent Moscow, had resisted the appointment of Mogherini at that time. At 41 and in government only since February, they saw her as lacking the political experience and weight to stand up to the Kremlin and also handicapped by Italy’s dependence on Russian energy.