Ukraine's opposition leaders urged hundreds of thousands of pro-Europe protesters at a rally yesterday to keep up pressure on President Viktor Yanukovich to sack his government and drop plans for closer ties with Russia.

The protesters, gathered on Kiev's Independence Square, are furious with the government for its decision to ditch a landmark pact with the EU in favour of a trade deal with Moscow.

Sunday's rally marks a further escalation in a weeks-long confrontation between authorities and protesters that has raised fears for political and economic stability in the country.

"This is a decisive moment when all Ukrainians have gathered here because they do not want to live in a country where corruption rules and where there is no justice," said world heavyweight boxing champion-turned-politician Vitaly Klitschko.

The opposition accuses Mr Yanukovich, who met Russian President Vladimir Putin on Friday, of preparing to take Ukraine into a Moscow-led customs union, which they see as an attempt to recreate the Soviet Union.

"We are on a razor's edge between a final plunge into cruel dictatorship and a return home to the European community," jailed opposition leader Yulia Tymoshenko said in an emotional message to the crowd read out by her daughter Yevgenia.

"There is a significantly greater chance of ending up in a medieval dictatorship; the choice is in your hands," said Tymoshenko, Yanukovich's main rival, who is serving a seven-year jail sentence for abuse of office in a case condemned by the West as politically motivated.