The ruling Party of the Regions is on course to win the largest amount of votes in the Ukraine's parliamentary poll with 36.6 per cent of the electorate having voted for President Viktor Yanukovych's party, according to partial results.

The United Opposition bloc, headed by Yulia Tymoshenko, the jailed former prime minister, came in second place with 21.0 per cent of Sunday's vote, 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," Mykola Azarov, prime minister, said.

The Communists were polling strongly in third place with 15.3 per cent, followed by 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, according to the partial results.

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.

Controversial jailing

The election to the 450-seat Verkhovna Rada is seen both as a warm-up for the 2015 presidential ballot and a chance for voters to pass judgement on the jailing of Tymoshenko, which has isolated Ukraine from European Union states.

Tymoshenko has been jailed through 2018 and is facing new charges related to fraud and tax evasion. There is also a separate murder investigation in which she has featured as a witness.

Al Jazeera's Rory Challands, reporting from Kiev, said two factors would determine how much dominant the ruling party would be in the new parliament.

"The first is whether the opposition can be unified," he said. "Two parties that have won members of parliament for the first time ... They'll be trying to work as well as they can with Batkivshchyna, the party of Tymoshenko.

"Also key is whether the Party of the Regions will have an outright majority. If they do, it will be very, very easy for them to dictate the future policy of Ukraine."

More than 3,700 foreign observers were in Ukraine to monitor the vote.