Ukraine's highest court on Thursday blocked the inauguration of Prime Minister Viktor Yanukovich, whose contested election has led to mass protests, and said it would examine a complaint by his liberal challenger.

The Supreme Court rejected the official publication of election results that showed Yanukovich had beaten Viktor Yushchenko in a run-off election last Sunday.

In its ruling, the Supreme Court appeared to turn the tide of events in favor of Yushchenko, who has brought thousands of supporters on to the streets after alleging he was cheated out of the election.

A president cannot be sworn in without the result being officially published.

"The court ruling bars the Central Election Commission from officially publishing the results of the election and proceeding with any other action connected with this," the court said in a statement.

The court said it would examine next Monday Yushchenko's complaint that the election of the Moscow-backed prime minister had been engineered by mass cheating.

Yushchenko vowed no let-up in protests to overturn the election result and pressed forward with plans for a national strike to bring transport and industry to a halt.

But in the divided state's eastern regions, which account for most of Ukraine's economic muscle, coal miners pledged support for Yanukovich and said they would not join any strike.

The strike, also intended to shut down schools and halt transit of goods, was not yet under way but Yushchenko's team said "decrees" launching it would be announced later in the day.

Some activists had already started blocking highways in four widely separated regions of the former Soviet state.

Under the court ruling, outgoing President Leonid Kuchma, who endorsed Yanukovich only after long reflection, would stay on in power for now.

Kuchma on Wednesday warned Ukraine could plunge into civil war and urged the West to stay out of the country's affairs.

PUTIN, EU AT ODDS

In The Hague, Ukraine's crisis dominated summit talks between Russian President Vladimir Putin and the European Union presidency, who are at odds on the issue.

Putin, who congratulated Yanukovich as the summit began, later said outsiders had no moral right to push Ukraine into "mayhem." Ukrainian courts, he said, should resolve any dispute.

Polish President Aleksander Kwasniewski also said he would head for Ukraine within days to help mediate. Poland, a NATO and EU member, is Ukraine's main European sponsor.

The West has made clear to Ukraine it regards the election as fraudulent. Apart from sharp EU criticism, the United States has warned Ukraine there could be consequences for their ties.

Election officials, defying calls by the West and tens of thousands of demonstrators on the streets of Kiev, declared Yanukovich the winner in the run-off.

"We will not leave this square until we secure victory," Yushchenko told at least 100,000 supporters crowded in to Kiev's Independence Square and spilling into adjacent streets.

"My team and I will stay here even if there are only 15 of us left. We will stand here until our victory," he said to applause and wild cheering.

As Ukraine seethed with turmoil for a fourth successive day, the central bank said it would support banks if they were hit by a run on deposits, sparked by political uncertainty.

PASSIONATE DIFFERENCES

The dispute reflects passionate differences over the orientation of Ukraine, a country of 47 million people that has a common history with Russia but also wants to grow closer to three new EU members on its borders.

Yanukovich sees closer ties with Russia as the key to future prosperity, while Yushchenko, popular in western and central regions, wants to move closer to the West while recognizing Moscow as a "strategic partner."

On Wednesday, Yushchenko aides said opposition activists had blocked main arteries in Ukraine at the start of strike action.

But another aide said on Thursday a program of civil disobedience was yet to get under way.

There was a different picture in eastern Ukraine, Yanukovich's power base, where heavy industry is concentrated.

"The miners will work and will continue to work. They know that without our labor the country cannot exist," said Igor Strelchenko, a trade union chief in the mining town of Donetsk.

Lithuania said Kuchma had asked it to act as a moderator.

Kiev's Independence Square and its main roads were again paralyzed by the mass protests as people of all ages and from different regions of Ukraine converged on the center. Some waved the national blue-and-yellow flag, but the dominant color was orange -- Yushchenko's campaign colors.

Source: CD/Agencies