EU leaders have given Russian president Vladimir Putin one week to stop attacking Ukraine or face more sanctions.

The latest ultimatum came after Ukrainian president Petro Poroshenko personally told the 28 presidents and PMs at a summit in Brussels on Saturday (30 August) that he is a hair’s breadth away from “full-scale war” with his neighbour.

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The summit conclusions corroborated his claim that last week saw an open “aggression by Russian armed forces on Ukrainian soil”.

The conclusions tasked the European Commission to present new sanctions options “within a week” and said they will include “a provision on the basis of which every person and institution dealing with the separatist groups in the Donbass [east Ukraine] will be listed”.

They did not spell out what will prompt the EU decision, referring only to “the evolution of the situation on the ground”.

“There is no precise criterion”, EU Council chairman Herman Van Rompuy told press.

For her part, German chancellor Angela Merkel noted that the Russian army’s incursion into Ukraine marks “a new step in the escalation”.

She added the upcoming sanctions will target the same areas as the previous round: Russia’s financial sector; exports of dual-use goods; sales of oil-drilling technology; and arms sales. "But we didn't go into details tonight. We didn't talk about names or specific measures", she said.

The one-week lag is designed to give Poroshenko a chance to propose a new peace plan in Kiev on Monday.

It will give EU countries’ experts time to haggle over details of the EU measures, with France, for one, keen to make sure new sanctions do not stop it from delivering warships to Russia.

French president Francois Hollande said the delay will also give European leaders a chance to co-ordinate with Nato partners at the alliance’s summit in Wales on Thursday and Friday.

Some EU countries, including Cyprus, Hungary, and Slovakia, voiced scepticism on further EU action.

But others, such as Lithuania, wanted to go much further.

Lithuanian president Dalia Grybauskaite told media that Russia “is in a state of war against countries that want to be closer to the European Union and that means, practically, that Russia is in a state of war against Europe. That means we have to help Ukraine … militarily”.

For the sceptics, some of whom had called for an impact assessment of existing EU measures before taking new steps, Merkel joked that: "Russia doesn't give regular updates of how much it [the EU sanctions regime] is hurting”.

For the hawks, Germany and France ruled out military assistance.

“We want a ceasefire, to stop the conflict, not to inflame it”, France's Hollande said.