KIEV: Ukraine's ruling party was on course Monday to win the most votes in legislative elections despite a challenge from the party of ex-premier Yulia Tymoshenko whose jailing sparked Western concerns.

The elections on Sunday for the 450-seat Verkhovna Rada chamber of parliament were a huge test for Ukraine's fragile democracy and already overshadowed by the imprisonment of Tymoshenko, who has now spent over a year in jail for abuse of power while in office.

The Regions Party of her arch-foe President Viktor Yanukovych was taking 36.6 per cent of the vote against 21.0 per cent for the opposition party of Tymoshenko, the central election commission said in a statement based on a 30 per cent vote count in the proportional system that will determine half the seats in the new parliament.

The ruling party was also on course to win around 110 seats out of the 225 seats that are being determined by first-past-the-post single mandate constituencies, an early analysis of the results showed.

“We are expecting that the Regions Party will take the majority in the new parliament,” Prime Minister Mykola Azarov said.

The Communists were polling strongly in third place with 15.3 per cent, followed by heavyweight boxing champion Vitali Klitschko's new UDAR (Punch) party on 12.6 per cent.

The ultra-nationalist Svoboda (Freedom) party was also due to break the five per cent threshold needed to make parliament and was polling 7.6 per cent, the partial results released by the central election commission said.

Ukraine's longest-running exit poll by the Democratic Initiative Foundation had earlier given a different outcome with the Regions Party leading with 28.1 per cent and Tymoshenko's alliance with 24.7 per cent.

Interpreting the make-up of the new parliament is difficult as dozens of independents are set to win single mandate seats and their affiliation will not become clear until parliament actually meets for its first session.

The Tymoshenko, Klitschko and Svoboda parties are expected to form an alliance in parliament but it is still unclear if this can stop the Regions Party taking an overall majority.

Klitschko admitted afterwards on national television he had hoped his party would have picked up more votes. He also blamed the disappointing result on dirty politics, saying that the “number of violations in the final week had exceed even what we had expected.”

Respected political analyst Volodymyr Fesenko said while the Regions Party would fall short of an overall majority it should be able to form one with the help of independent but loyal candidates from the single-mandate constituencies.

“Thus it seems the question of the majority is almost decided,” the director of the Penta Research Institute said on Channel One television.

The elections were the first big vote in Ukraine — wedged between the European Union and Russia — since 2004 Orange Revolution co-leader Tymoshenko lost a close presidential ballot to Yanukovych in early 2010.

Tymoshenko, who is currently outside of prison receiving treatment in hospital, voted while lying down in bed in the presence of two international observers.

Western nations fear the October 2011 abuse of power conviction for Tymoshenko is retribution by the president and the European Union has largely shunned Yanukovych in recent months.

Concerns that two years of Yanukovych in power have sidelined Ukraine from its democratic course prompted US Secretary of State Hillary Clinton and EU foreign policy chief Catherine Ashton to issue a rare joint appeal to the ruling elite to ensure democratic polls.

A big loser in the polls appears to be the recently-retired football star Andriy Shevchenko who had astonished his fans by becoming a leading figure in the Ukraine Forward! party of former Tymoshenko ally Natalya Korolevska.

According to the initial results, it was set to win only 1.7 per cent of the vote and a handful of single mandate seats, leaving the former AC Milan star's political future uncertain.