Ukrainian PM's lead hit by 'vote-rigging' row

But Mr Yushchenko, who was put ahead of his rival in exit polls, accused the authorities of vote rigging.

Central Election Commission figures showed Mr Yanukovich had won 49.57 of the vote and Mr Yushchenko 46.57 per cent, with 98.23 per cent of the ballots counted.

Addressing a crowd of some 10,000 people in the main square of the capital, Kiev, Mr Yushchenko accused election officials of falsifying the results.

"The people’s will cannot be broken. People’s votes cannot be stolen," he told the cheering crowd.

Riot police guarded the Central Election Commission office and several armoured vehicles were deployed. Ambulances were parked near the square.

Pro-Yushchenko MP Ohleh Rybachuk said the opposition demanded an urgent parliamentary session to call for a re-count and a no-confidence vote in the Election Commission.

The election was seen as determining whether the ex-Soviet republic tilts toward the West or its traditional patron, Russia.

The bitter campaign also sparked fears that Ukraine could erupt into civil unrest as distrust in the government’s ability to conduct a credible vote grew.

One exit poll, conducted by anonymous questionnaires under a programme funded by several Western governments, including the United States, said the Western-leaning reformer Mr Yushchenko had 54 per cent of the vote and Mr Yanukovich trailed with 43 per cent. Another poll put Mr Yushchenko ahead by only 49.4 to 45.9 per cent.