The centre-right party of Bulgarian former premier Boyko Borissov, which is blamed for presiding over years of corruption, is likely to be the winner of parliamentary elections, according to an exit poll.

The survey by Gallup International showed the GERB party earning 24.6% support, apparently edging out the reformist We Continue the Change pro-western party of former prime minister Kiril Petkov, which is expected to poll 18.9%.

The predicted percentage will not be enough for Mr Borissov’s party to form a one-party government, and the chances for a GERB-led coalition are slim.

The exit poll also predicted that eight parties could pass the 4% threshold to enter a fragmented parliament with populist and pro-Russia groups showing increased gains.

The European Union nation’s fourth election in 18 months was marked by a raging war nearby, political instability and economic hardships in the bloc’s poorest member.

A low turnout reflected voter apathy.

Mr Petkov conceded defeat late on Sunday.

“We lost the election, albeit by a small margin, and now GERB has the responsibility to form a coalition and govern the country,” he said.

It could take days before the final official results are announced.

If they confirm the exit poll, Mr Borissov will be handed a mandate to form his fourth cabinet.

It will be an uphill task for him to produce a stable governing coalition, however, since most political groups have in advance rejected any co-operation with his GERB party, which presided over years of corruption that hampered development.

The early election came after a fragile coalition led by Mr Petkov lost a no-confidence vote in June.

He claimed afterwards that Moscow had used “hybrid war” tactics to bring down his government after it refused to pay gas bills in roubles and ordered an expulsion of Russian diplomats from Bulgaria.