Ukraine's Supreme Court has barred official publication of the results of Sunday's presidential election until it considers a challenge to the balloting.
The announcement Thursday, bars any attempt to inaugurate Prime Minister Viktor Yanukovych. Electoral officials Wednesday said the prime minister won by a slim margin.
Meanwhile, demonstrators continue to stage massive rallies in Kiev and other cities in support of Ukrainian opposition leader Viktor Yushchenko. The opposition is alleging widespread fraud, and international observers have expressed serious concern about the balloting.
U.S. Secretary of State Colin Powell said Wednesday the results cannot be accepted as legitimate until the widespread reports of electoral fraud are investigated.
In another development, Ukraine's deputy economy minister resigned Thursday over disagreements with authorities about the election.
Some information for this story provided by AFP and Reuters.