UK Foreign Secretary William Hague has urged Russia to attend talks at a planned international summit in Paris on Thursday ready to de-escalate the Ukraine crisis.

The meeting, which was set to discuss the Lebanon, will include Hague and other EU leaders, US Secretary of State John Kerry and, it is hoped, Russia's Sergei Lavrov.

It will come the day after a special European summit aimed at hammering out an agreed package of measures aimed at Moscow should tensions not ease in the region.

Hague told MPs in the Commons that he was ready to agree "targeted measures" against Russia but he did not spell out further details. He did, however, play down reports that the UK was ruling out tough economic and financial sanctions.

The suggestion stemmed from a snatched photograph of a document being carried into Downing Street by an official on Monday night and which said the UK "should not support for now trade sanctions or close London's financial centre to Russians".

But Hague told MPs: "I want to make it absolutely clear that anything that is written in one document that is being carried by one official is not necessarily any guide to the decisions that will be made by Her Majesty's government, and our options remain very much open on this subject."

However, there were continuing signs that the US was frustrated that the reaction from the EU states was less robust than that coming from the White House, because of the EU's economic interests.

Kerry has been eager to map out specific sanctions which might be levied against Moscow, while the UK continues to hold back from outlining specifics preferring to wait until the EU summit to ensure all states "speak with one voice."

Meanwhile, Hague repeated his warning over the seriousness of the situation in Ukraine saying there was a risk that any "escalation or miscalculation" could pose a threat "to the hard won peace and security in Europe".

He commended the Ukrainian government for "responding to this extreme situation with a refusal to be provoked" and he dismissed claims the Russian intervention had been at the intervention of former Ukraine president Viktor Yanukovych, currently in Russia.

Claiming Yanukovych had "abandoned his post", he added: "Suggestions that a president who fled his country then has any authority whatsoever to invite forces of another country in is baseless".

Labour's Douglas Alexander backed the government but urged ministers to outline more specific measures aimed at Moscow, or: "the UK's words will count for little".