Ukraine's Supreme Court gave the prime minister's legal team until Tuesday to study evidence of fraud presented by the opposition in last week's presidential election, while outgoing President Leonid Kuchma (search) endorsed the idea of a new vote "to preserve peace" in the bitterly divided former Soviet republic.

Kuchma, who has called for compromise throughout the crisis, said Monday a new vote might be the only way to resolve the weeklong standoff in which tens of thousands of opposition supporters have blocked official buildings in the capital and eastern provinces are threatening to seek autonomy.

The demonstrations continued Monday night as throngs packed snowy Kiev's Independence Square, waving Ukrainian flags and orange flags showing their support for opposition candidate Viktor Yushchenko (search), who addressed them.

The defense minister said the army would not use force against the people, the Interfax news agency reported.

"If we really want to preserve peace and accord, if we really want to build a democratic state ... let's hold new elections," Kuchma was quoted as saying by Interfax. He said Ukraine needs a "legitimate president."

Yushchenko, who claims he was robbed of victory, has called for a new election on Dec. 12 under international auspices.

Ukrainian Prime Minister Viktor Yanukovych (search), who was declared winner of the disputed Nov. 21 runoff vote by the nation's Central Election Commission, offered lukewarm support for a new vote, saying he would accept it if the opposition's allegations of fraud were proven.

But Yanukovych, who is supported by Kuchma and the Kremlin, added that he had not seen any evidence of fraud, and he suggested that another vote would be illegal.

"If there is evidence of falsification, I will agree with this decision," Yanukovych said while meeting with Kuchma and top officials from eastern Ukraine. He stressed allegations of fraud must be proven by a "clear, honest and transparent" investigation.

Yanukovych also said he would call on voters in Donetsk (search) and Luhansk (search) — two industrial regions in Ukraine's east where he has strong backing — to participate. Lawmakers in Donetsk, Yanukovych's native region, voted Sunday to hold a referendum on autonomy for the surrounding province.

The United States and the European Union have agreed the presidential election results were marred by massive fraud and cannot be accepted. Secretary of State Colin Powell told Kuchma on Monday it was important to keep the country intact.

"If we can keep things calm and allow the leaders and the politicians and members of the international community who are trying to help the Ukrainians all come together then, hopefully, a peaceful solution will be found," Powell said in Washington.

At the White House, presidential spokesman Scott McClellan called on the international community to unite in support of a peaceful, democratic process in Ukraine "and of Ukraine's sovereignty, independence and territorial integrity."

Yushchenko's team is asking the Supreme Court to throw out the presidential election results, cancel the election commission's decision and name Yushchenko the victor because he narrowly won the Oct. 31 first-round vote.

The Supreme Court began considering his appeal but said Monday a decision could take days.

The ruling could pave the way for a new vote or remove the only barrier to the inauguration of Yanukovych, who was declared the winner by a margin of 871,402 votes.

Justice Anatoliy Yarema said the court would give Yanukovych's lawyers until 10 a.m. Tuesday to study additional evidence presented by Yushchenko's team.

Under Ukrainian legislation, the court cannot rule on the overall results but can declare results invalid in individual precincts. A Yushchenko aide, Mykola Katerinchuk, said the appeal focused on results in eight eastern and southern Ukrainian regions — more than 15 million votes, almost half of the total cast in the runoff.

A key Yanukovych aide, Stepan Havrysh, said his side was expecting a "fair decision ... taken without emotion."

"I expect that the judges will not overstep the law because it could end in a civil war," he said.

Thousands of supporters of both sides massed outside the court as the session started.

Yushchenko has rejected government appeals to call off the tens of thousands of protesters who have thronged the capital since last week, instead urging his backers to maintain their round-the-clock vigil and blockades of the Cabinet building and the presidential administration.

Yushchenko's more radical ally, Yuliya Tymoshenko (search), also warned that opposition supporters would block Kuchma's movements if he did not fire Yanukovych and governors of eastern regions threatening to push for self-rule by late Monday.

The crisis has deepened the political tug-of-war between the West and Moscow, which considers this energy-dependent nation of 48 million people part of its sphere of influence and a buffer between Russia and NATO's eastern flank.

Yushchenko, whose wife is U.S.-born, says he wants to push the country to greater integration with Western Europe, and he has suggested he would seek NATO membership. His critics worry he will alienate Ukraine from Russia, its key trade partner and main energy supplier.

Yanukovych was openly backed by Russian President Vladimir Putin and was expected to pursue closer ties with Moscow. He drew his support from Ukraine's pro-Russian, heavily industrialized eastern half, while Yushchenko's stronghold was the west, a traditional center of nationalism.

The Donetsk referendum would ask voters to demand the status of a republic for the region, which would require changing Ukraine's constitution to allow for stronger self-rule for its provinces. While such changes could face serious opposition, the vote suggested Ukraine's rift could deepen if the election results were overturned.