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 today (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 (Oleh Haiduk) resigned today over disagreements with authorities about the election.
The leaders of Russia and the European Union have acknowledged sharp differences over Ukraine's disputed presidential election.
Russian President Vladimir Putin and Dutch Prime Minister Jan Peter Balkenende -- whose country holds the rotating EU presidency -- told reporters each side favors a different approach to solving the Ukrainian crisis.
Russian President Vladimir Putin called for a solution through the courts and within the framework of Ukraine's constitution.
Prime Minister Viktor Yanukovych -- who was backed by Mr. Putin -- has been declared the winner of Sunday's voting.
Mr. Balkenende reaffirmed the EU view that the vote failed to meet international standards because of widespread voting fraud.
In another development, Russia and the EU failed to finish negotiations on a so-called "strategic partnership."
Mr. Putin said he expects the two sides will be able to conclude the negotiations to formalize EU-Russian ties by the next summit in May.