Ukraine crisis: Russia is deliberately 'violating the independence and sovereignty of Ukraine', says William Hague

British Foreign Secretary William Hague has accused Russia of deliberately destabilising eastern Ukraine.

Speaking on Monday at a meeting of EU foreign ministers in Luxemburg to discuss the crisis, Mr Hague dismissed denials of Russian involvement and called for further sanctions against Moscow.

“There can't really be any real doubt that this is something that has been planned and brought about by Russia,” he said.

“I don't think denials of Russian involvement have a shred of credibility.”

He added that events had all the hallmarks of Russia's actions to seize Crimea from Ukraine: “It has all the appearance of a further gross deliberate, premeditated violation of the independence and sovereignty of Ukraine.”

Mr Hague said he would be arguing for the EU to take further measures to sanction Russia for its actions. A so-called “third phase” of EU sanctions is expected to include restrictions on trade and finance with Russia, potentially with wide-reaching repercussions for the Russian and EU economies.

Downing Street said David Cameron interrupted his Easter holiday in Lanzarote to discuss the “deteriorating situation in Ukraine” with Mr Hague.

The foreign secretary’s comments came as pro-Russian forces showed little sign of complying with a deadline set by the Ukrainian government, ordering them to disarm and end their occupation of state buildings by 9am (6am GMT) Monday.

Oleksander Turchinov, the acting president of Ukraine, on Sunday warned rebels that a full-scale security operation, including the army, would be unleashed unless they met the deadline.

But according to reports in the flashpoint city of Slovyansk, where armed men have seized two government buildings, there was no outward sign the rebels were complying with the ultimatum.

And in the city of Horlivka at least 100 pro-Russian separatists attacked the police headquarters, a witness told Reuters.

Video footage on Ukrainian television showed an ambulance treating people who were apparently injured during the attack on the main police building in the Donetsk region city, which has a population of around 300,000 people.

Russian Foreign Ministry Sergei Lavrov on Monday denied Ukrainian and US allegations that Russia had undercover agents fomenting unrest in eastern Ukraine, and said he was seeking explanation of media reports that the director of the CIA, John Brennan, had visited Kiev.

Speaking at a news conference after meeting his Sudanese counterpart, he said that Ukraine's Russian-speaking eastern regions should be involved in drafting the constitution that should be put to a referendum, mooted by Kiev, on the type of state Ukraine should be.

Lavrov said it was not in Russia's interests for Ukraine to break up, but that Moscow wanted all citizens of the country to be given equal treatment by Kiev.

Additional reporting by agencies