Both sides in Ukraine’s disputed presidential elections have warned of the threat of civil conflict.

The pro-liberal opposition challenger, Viktor Yushchenko, said that the proclamation of victory for Viktor Yanukovich put Ukraine ‘on the brink of civil war.’

Mr Yushchenko said he does not recognise the election of the country's prime minister as president and called for a nation-wide political strike.

Ukraine's outgoing president also warned that the opposition may be plotting a coup after his pro-Moscow prime minister was declared winner of a disputed election.

As tensions mount in the country, Leonid Kuchma urged all sides to engage in political dialogue.

Meanwhile, the US Secretary of State, Colin Powell, has said the United States does not accept the results of the election.

Mr Powell urged Ukraine's leaders to ‘respond immediately’ or there would be consequences in the relationship between the two countries.

Yanukovich won Ukraine poll, commission says

This afternoon, the election commission announced that the pro-Russian Prime Minister, Viktor Yanukovich, won Sunday's disputed presidential election.

Pro-government supporters surrounded the electoral commission in the capital Kiev as thousands of supporters of the opposition leader, Viktor Yushchenko, marched towards the building.

The opposition says the election was rigged.

The head of the commission, Serhiy Kivalov, told reporters that Mr Yanukovich won by a margin of almost 3% with 49.46% of the vote to Mr Yushchenko's 46.61%.

Yushchenko offers to rerun election

Earlier, Mr Yushchenko said he was prepared to rerun a disputed presidential election provided it was overseen by honest officials.

He made the announcement to tens of thousands of supporters massed in Kiev's main square for the third day in a row.

Separately, outgoing President Leonid Kuchma categorically ruled out the use of force against the demonstrators massed outside his office.

Earlier, six municipalities, including Lviv and the capital, rejected the official results to date.

The Dutch EU Presidency is sending a senior diplomat to Kiev to meet Mr Yushchenko, President Kuchma and the parliamentary speaker.

The EU and the chairman of the OSCE had called for a delay in announcing full results of Sunday's presidential poll pending a review of the election.