Ukraine’s election commission on Monday declared Prime Minister Viktor Yanukovich the winner of Sunday’s presidential election run-off, despite pro-Western opposition leader Viktor Yushchenko’s clear lead in independent exit polls.

The opposition has strongly rejected the result, saying the election was rigged.

The European Union expressed serious concern about the outcome of the election, and has called on Kiev authorities to review the results.

Thousands of opposition supporters crowded onto the capital’s landmark Independence Square, from where Mr Yushchenko called for civil protest.

“We are launching an organised movement of civil resistance,” he said to cheers from the crowd. “The campaign is only just beginning. Don’t leave Independence Square until victory.”

Baring the opposition’s trademark orange colour, the crowds shouted:
“Yushchenko president!” and “Shame on the government!”

Organisers said they would carry on until parliament annulled the results of the election.

There were special cheers when news filtered in that Kiev city council — along with two other cities — had refused to recognise the election results.

Security was tight around the capital, with riot forces standing guard at the central election commission near Independence Square.

A counter-demonstration with Russian flags was staged in the pro-Moscow Black Sea city of Simferopol, were tens of thousands celebrated Prime Minister Viktor Yanukovich’s declared victory.

According to the central electoral commission Mr Yanukovich won 49.42 percent of the vote, compared with 46.7 for Mr Yushchenko, with 99.38 percent of results in.

Russian President Vladimir Putin telephoned Mr Yanukovich to congratulate him on his “convincing” win.

But Jacek Saryusz-Wolski, the Polish deputy speaker of the European parliament, said on Monday the election had been rigged in favour of the pro-Russian Prime Minister.

“There was no victory for Yanukovich. This election was fraudulent,” Saryusz-Wolski, an election observer, said.

He warned: “This false result will be challenged in the courts by the party which really won, and international public opinion, including in the European Union and the European Parliament, will not be indifferent.”

Meanwhile, the European Union’s Dutch presidency called on EU states to summon Kiev’s ambassadors to voice their concern.

Ukraine has been one of the EU’s new neighbours since May this year, when the bloc took in 10 mostly ex-communist countries as members, and EU leaders have fostered closer ties with Kiev.

A US State Department official said Washington saw “serious flaws and problems with this election”.