Ukrainian police fired tear gas at pro-Europe demonstrators and authorities sought to isolate jailed opposition leader Yulia Tymoshenko as she launched a hunger strike over Kiev's rejection of a European trade pact under pressure from Moscow.

European Union leaders issued unusually strong criticism of Russia on Monday, stressing the offer to Ukraine remained on the table despite little indication it would sign the pact with the EU at a summit on Friday as originally planned.

The EU  had waned the release of Tymoshenko if the trade agreement was to continue, a provision rejected by Ukraine's government who instead turned to Russia to forge a deal.

Police clashed with protesters who gathered for a second day in Kiev and speakers urged people to stay on the streets, although numbers were smaller on Sunday, the largest turnout since a pro-democracy "Orange Revolution" nine years ago.

President Viktor Yanukovich, acting to defuse pressure from the streets, which denied him the presidency the first time in 2005, said rejecting the pact had been difficult but unavoidable -- implying EU rules were too tough on the fragile economy.

He pledged to create "a society of European standards."

"My policies on this path always have been, and will continue to be, consistent," he said in a television address which did not mention relations with Russia or refer to EU pressure to release Tymoshenko, his fiercest opponent.

Within minutes of his address, a second round of clashes broke out near Kiev's European Square in which special force units used batons and tear gas for several minutes against a small group of protesters away from the main body of the rally.

Hunger strike

Former economy minister Arseny Yatsenyuk, one of the opposition leaders, denounced Yanukovich's address as an attempt "to justify his absurd policy" and Tymoshenko's lawyer told the crowd she would stop eating to persuade Yanukovich to change his mind.

"As a sign of unity with you, I declare an unlimited hunger strike with the demand to Yanukovich to sign the association agreement," declared the 52-year-old Tymoshenko in a message to the protesters read out by her defence lawyer, Serhiy Vlasenko.

The Ukraine prison service said it was stopping all visits to patients in the hospital in the town of Kharkiv where Tymoshenko is being treated, citing a health risk because of an outbreak of respiratory infection in the town.

Public health regulations meant that mass meetings would be suspended too, it said, - something that might rule out any protest demonstrations on behalf of Tymoshenko.

Yevgenia, Tymoshenko's 32-year-old daughter, said that when she went to visit her mother on Monday she was refused entry.

"This is the deliberate, unlawful isolation of my mother," she was quoted by the web site of her mother's party as saying.

Source: Agencies