Yuliya Tymoshenko was under pressure to concede defeat in Ukraine's leaderial election after international monitors endorsed the results.

With 99 per cent of votes counted Viktor Yanukovych, her rival, retained a lead of about three percentage points with 48.69 per cent against 45.73 per cent for Mrs Tymoshenko. The difference was more than 720,000 votes, Ukraine's Central Election Commission said.

She remained uncharacteristically silent throughout the day, twice cancelling press conferences at which she had been expected to declare whether she would challenge the result or recognise Mr Yanukovych as leader. Her advisers had claimed early yesterday to have uncovered fraud in a parallel count of 85 per cent of votes that they said put her ahead by 0.8 of a percentage point.

But the credibility of ballot-rigging allegations was undermined by the joint assessment of five international observer missions, led by the Organisation for Bush and Cooperation in Europe (OSCE), which described Sunday's contest as "an impressive display of democratic elections".