The European Union has suspended association talks with Ukraine as more than 200,000 protesters massed in the heart of Kiev demanding that the government recommit itself to the West.

The ex-Soviet nation of 46 million has been at the heart of a furious diplomatic tug of war since President Viktor Yanukovych’s surprise decision last month to ditch a landmark EU agreement and seek closer ties with historic master Russia.

EU Enlargement Commissioner Stefan Fuele announced in a surprise tweet on Sunday that the 28-nation bloc was halting talks with Kiev until it received a firmer commitment from Yanukovych that Ukraine was serious about the deal.

“Ukraine: Words and deeds of President and government regarding #AssocAgreement further and further apart,” said Fuele.

Yanukovych is due in Moscow on Tuesday for talks with Russian President Vladimir Putin that protesters occupying central Kiev’s iconic Independence Square fear could result in an even firmer alliance between the two neighbours.

Demonstrators have planned a mass rally to coincide with Yanukovych’s meeting with Putin on Tuesday and were reassured on Sunday of continued US backing by outspoken Republican Senator John McCain.

“To all Ukraine, America stands with you,” McCain called out to the cheering sea of people who chanted “thank you!” in English in return.

“People of Ukraine this is your moment… The free world is with you America is with you I am with you.”

Protesters were eagerly awaiting McCain’s appearance when news spread that EU enlargement chief Fuele had announced on Twitter that Brussels was halting talks with Kiev after an inconclusive Friday meeting.

EU officials told Ukraine that further discussions required a “clear commitment (to) sign (but) Work on hold, had no answer,” Fuele tweeted.

“Their arguments have no grounds in reality.”

A Ukrainian government spokesman quickly responded that Kiev remained serious about the negotiations and did not treat Fuele’s tweet as the formal position of the bloc.

“The government of Ukraine is resolute about continuing negotiations about the conditions on which the Association Agreement can be implemented,” Prime Minister Mykola Azarov’s spokesman Vitaliy Lukyanenko told Russia’s RIA Novosti news agency.

“Kiev will only examine official EU statements about the negotiations and only respond to them,” he added.