Yushchenko, who had been declared Sunday a loser to acting Prime Minister Viktor Yanukovich, called on his supporters here to march to the parliament building, the Rada, to demand the annulment of Sunday's election results.

"I ask you in an organized and peaceful manner to start marching towards the Rada (parliament)," Yushchenko told the Kiev crowd.

Yushchenko's supporters took to the street after official results released Monday show that Viktor Yanukovich won the presidential run-off in this former Soviet republic by a three percent margin.

The opposition and international observers have said the vote was rigged.

Reports here said the western opposition stronghold of Lviv also saw protesters in the street to demand that Yushchenko be recognized the winner of the election.

Ukraine's parliament was due to meet in an extraordinary session later Tuesday, after the municipal assembly of Kiev refused to recognize the official ballot results and urged the legislature to follow suit.