The Ukrainian parliament meeting in emergency session has declared last Sunday's presidential vote invalid because it was fraudulent and at odds with the will of the people.
The vote was backed by over 300 deputies supporting both candidates with about 100 abstentions and only one vote against the resolution.
100,000 supporters of opposition candidate Viktor Yushchenko, who says he was cheated out of the presidency by fraud, massed outside the parliament building during the debate.
The parliament cannot overturn the result but its views may carry weight with the Supreme Court which meets on Monday to examine the fraud claims.
Meanwhile, the EU has urged Ukraine to hold new elections. The Dutch Foreign Minister, Ben Bot, said the elections should be held before the end of the year.
Opposition supporters are continuing to block key government buildings in Kiev today after a first meeting between the two candidates last night ended without agreement.
Addressing a sea of supporters, Viktor Yushchenko said he had presented prime minister Yanukovich with an ultimatum: give quick approval to a new election or face action on the streets.
He called for a fresh presidential vote on 12 December.
Russia, which has openly backed Viktor Yanukovich and has been exchanging angry rhetoric with the West over the poll, was represented at the talks by parliament speaker Boris Gryzlov.
EU foreign policy chief Javier Solana, who was also present, said he had made it clear that he believed the vote was fraudulent and that future relations depended on a 'democratic' resolution.
Ukraine's national television news, which had been giving mostly positive coverage of Yanukovich, has begun to feature the opposition in recent days.
