Ukraine's rival leaders battle on

The street protests echo the 2004 Orange Revolution

Supporters of Ukrainian PM Viktor Yanukovych are keeping up their protest outside parliament in Kiev against his rival, President Viktor Yushchenko.

The power struggle continued over the Easter holiday, with Mr Yushchenko refusing to revoke his decision to call a snap election for 27 May.

The constitutional court is due to consider his decision later this week.

Mr Yushchenko accuses Mr Yanukovych of undermining democracy by luring deputies to his bloc in parliament.

In an Easter address to the nation, Mr Yushchenko said Mr Yanukovych's ruling coalition had been "artificially and illegally beefed up step-by-step to achieve 300 votes" - the number required to overrule presidential vetoes.

Pro-Yanukovych deputies hit back at an extraordinary session on Monday, adopting a resolution which accused the president of putting pressure on constitutional court judges, Interfax news agency reported.

Mr Yanukovych's power base is the mainly Russian-speaking east of Ukraine. He has told the cabinet not to prepare for a snap election until the constitutional court rules on the dispute.

The latest escalation of the long-running power struggle began on 2 April, when Mr Yushchenko ordered the dissolution of parliament and the 27 May election. His power base is in western Ukraine, where support for Western-style liberal reforms is strong.

The rivalry started during the 2004 Orange Revolution, which eventually swept Mr Yushchenko into power.