BRUSSELS (Reuters) - Ukraine's October 28 parliamentary election was marred by a delayed vote count and other irregularities, the European Union said on Monday.

The criticism by the bloc - which has frozen a trade deal with Ukraine because of concerns over the country's political and justice systems - came a day after final election results showed the ruling party would likely keep its grip on parliament.

President Viktor Yanukovich's Party of the Regions remained the biggest party in the 450-seat parliament, gaining an overall 185 seats, but was thought likely to retain control with support from communists and independents.

"We express our concern about the conduct of the post electoral process, which was marred by irregularities, delays in the vote count and lack of transparency in the electoral commissions," EU foreign affairs chief Catherine Ashton and enlargement commissioner Stefan Fule said in a statement.

The EU comments came on top of earlier criticism of the build-up to the election and the vote itself.

Other problems already identified in a report by the Organisation for Security and Cooperation in Europe ranged from biased media coverage to a lack of transparency in financing.

The European Union and Ukraine initialed an agreement in March on greater political and economic integration, including trade, investment and movement of capital.

But the 27 EU governments and the European Parliament have yet to sign the accord because of concern over the former Soviet country's elections, judicial system and arrest of opposition leaders.

The election took place while the country's most prominent opposition leader, former Prime Minister Yulia Tymoshenko, served a seven-year sentence for abuse of office and awaited a new trial on charges of tax evasion and embezzlement.

After opposition rallies complaining of a crooked vote count, election authorities announced a re-vote in five individual electoral districts.

(Reporting By Sebastian Moffett; Editing by Andrew Heavens)