Ukrainian opposition party Batkyvshchina (Fatherland) plans to challenge in court the results of the local and regional elections in several regions, Mykola Tomenko, deputy head of the party said.

Ukrainians are going to polls on Sunday to cast their ballots in local and regional elections widely seen as a popularity test for President Viktor Yanukovych.

Batkyvshchina party led by ex-premier Yulia Tymoshenko who had lost presidential elections to Yanukovych early this year claimed that from 20% to 30% of polling stations across Ukraine did not open on time while local authorities failed to ensure normal organizational work on the day of voting.

Analysts say that Tymoshenko's Batkyvshchina party would focus on winning in its traditional strongholds in western and central parts of Ukraine. However, she would face bitter rivalry from the ultra-right nationalist Svoboda Party led by Oleh Tyahnybok.

The pro-presidential Party of Regions, which has no absolute parliamentary majority, is seeking to strengthen its positions across the country. The elections are also seen as a dress rehearsal for the forthcoming parliamentary polls.

The main rivals of the Party of Regions would be its parliament coalition allies, Sergey Tigipko's Strong Ukraine Party and the Communist Party of Ukraine.

According to recent media reports, the Party of Regions has the highest average support of 30%, compared with 8% of Tymoshenko's party. Strong Ukraine is forecasted to receive some 7% of the vote, communists and Svoboda Party are thought to garner about 3% each.

All the parties will clash to win over undecided voters, who make up a hefty 20%.

There is no minimum turnout for the election to be considered valid