Meanwhile, Yanukovych has filed a complaint today with electoral authorities contesting results of the 26 December presidential vote, which he lost.
Central Election Commission spokeswoman Zoya Charikova said today the complaint, handed in late yesterday, lists alleged violations of election law in all Ukraine's 225 electoral districts.
Charikova said the commission has two days to examine the appeal.
If it turns down the complaint, Yanukovych can appeal to the Supreme Court, something he has vowed to do if necessary.Blockade Of Government Building
Cabinet Secretary Anatoliy Tolstoukhov made the announcement of the postponement of today's government meeting without giving any details.
The winner of Ukraine's presidential election, Viktor Yushchenko, last night called on his supporters to blockade government headquarters to prevent his defeated rival from leading the cabinet meeting.
Yushchenko made the call during a rally yesterday evening in Kyiv's Independence Square.
"I ask you to strengthen a blockade of the government building tomorrow from early in the morning," Yushchenko told the crowd.
Yushchenko called Yanukovych's government illegitimate and said Yanukovych has no right to remain in office.
The Ukrainian parliament weeks ago passed a motion of no confidence in Yanukovych's government, but lame duck President Leonid Kuchma has so far refused to dismiss the prime minister.
The Yushchenko rally was held after electoral authorities released preliminary final results showing Yushchenko defeating Yanukovych in the 26 December repeat runoff vote by some 2.3 million votes -- 51.99 percent to 44.19 percent.
The Council of Europe, a pro-democracy and human rights group of which Ukraine is a member, has called on all sides to accept the election results.
(Reuters/AP/AFP)Recent Stories:"Ukraine: Yushchenko Wins, But Country Does Not Have A New President Yet""Ukrainian Authorities Declare Yushchenko Winner""Yanukovych Pledges To Challenge Ukraine's Vote Results""Analysis: Will Ukraine Now Orient Itself Toward The West?""Ukraine's Presidential Election Appears To Go Smoothly"[For more RFE/RL coverage and analysis, see our dedicated "Ukraine's Disputed Election" website.]