Vladimir Putin, the Russian president, agreed in a telephone conversation with the German chancellor, Gerhard Schröder, to respect the outcome of a fresh election if Ukraine decided to hold one, the German government said today.

The news came as Ukraine's supreme court continued to consider allegations of electoral fraud in the November 21 run-off election between the pro-western opposition candidate, Viktor Yushchenko, and his Moscow-backed opponent, Viktor Yanukovich.

Leonid Kuchma, the country's outgoing president, yesterday backed the idea of a new poll to defuse the week long standoff that has threatened to split Ukraine. The opposition has demanded assurances that any new vote would be held quickly.

The Russian parliamentary speaker, Boris Gryzlov, today questioned the future of Ukraine as Mr Yushchenko's supporters massed for an eighth consecutive day of protest in the country's capital, Kiev.

Mr Gryzlov, who took part in last week's meeting between Mr Yushchenko and Mr Yanukovich, told reporters: "The situation there is heading towards a split or towards bloodshed ... I see no other way the situation could develop."

Ukraine's parliament today convened to debate the growing threat to the unity of the former Soviet republic. The simultaneous sessions of the highest judicial and legislative branches came amid rising support for a new election to take place as the only way to avoid splitting Ukraine into a pro-Russian east and pro-Europe west.

The government has been paralysed since allegations of electoral fraud brought hundreds of thousands onto the streets of Kiev in support of Mr Yushchenko, who was declared to have lost the ballot.

Ukraine's eastern Russian-speaking regions - where support for Mr Yanukovich, declared the victor, is strong - reacted to the protests with threates to seek autonomy.

In the country's parliament, the speaker, Volodymyr Lytvyn, criticised "many state, regional and local officials in the east and south of the country for inciting separatism ... and unconstitutional and illegal aspirations for independence and autonomy".

He said calls for new autonomous regions in Ukraine were "illegal and punishable under the criminal code". The opposition has asked the supreme court to annul the election results, which said Mr Yanukovich had won by a margin of 871,402 votes. Under Ukrainian legislation, the court cannot rule on the overall results, but can declare results invalid in individual precincts.

The appeal focuses on the results from eight eastern and southern regions, accounting for more than 15m votes - almost half of the total cast in the runoff.

Opposition officials are asking the court to declare Mr Yushchenko the winner, based on his winning a narrow plurality of the votes in the first round on October 31. They have also pledged to seek a parliamentary vote of no-confidence in Mr Yanukovich's government.

The west has refused to recognise the election results, while Russia, which still yields considerable influence over Ukraine, congratulated Mr Yanukovich on his apparent victory. On Saturday, Ukraine's parliament passed a non-binding declaration, declaring the vote invalid.

Mr Yanukovich yesterday said he would support a revote if allegations of fraud were proven, but added he had yet to see such proof.

Meanwhile, Mr Yushchenko urged tens of thousands of supporters in Kiev to maintain their vigil despite the freezing temperatures. Early today, they warmed themselves around fires and sang Ukrainian folk songs as fresh snow fell on the sprawling tent camps housing them.

Mr Yanukovich's native Donetsk province has scheduled an autonomy referendum for Sunday, and other eastern regions have threatened to follow suit.

Mr Yushchenko and his allies have urged Mr Kuchma to sack the separatist governors, along with Ukraine's chief prosecutor for his failure to open a criminal investigation against them. Mr Kuchma has warned that "we cannot in any instance allow the disintegration or division of Ukraine".

The political crisis has sparked fears that Ukraine - which has a population of 48 million and is the fastest growing economy in Europe - could plunge into economic turmoil. Mr Kuchma warned that the country's financial system could "fall apart like a house of cards" in "a few days" under the impact of protests.

Many Ukrainians in the east, worried by the rising instability, have waited in long lines to exchange the national currency, hryvna, for US dollars.

Yesterday, the country's central bank set limits on dollar sales to companies and individuals, ordering commercial banks to end early deposit withdrawals. It also set limits on withdrawals from cash machines. Bank officials said the measures would be in place until December 31.