BELGRADE (Reuters) - Serbia jailed a veteran of the 1990s Yugoslav wars on charges of spying for Croatia, the latest of several tit-for-tat moves in which relations between the former foes have fallen to their lowest ebb since the conflict ended in 1995.

The Serbian High Court on Tuesday accepted a plea bargain by Cedo Colovic, 57, a former artillery officer who served with the military of the breakaway Serb republic in Croatia between 1991 and 1993. He was sentenced to three years in jail.

Colovic’s arrest on Friday was widely seen as a response to moves in Croatia, which votes in a general election on Sunday, to publicly rehabilitate controversial figures from the past, causing consternation in Serbia.

The worsening relations between the two threaten to derail Brussels’s plans to cajole the seven Yugoslav successor states toward further European integration since European Union member Croatia has the power to block or slow Serbia’s progress toward EU membership. Slovenia, another ex-Yugoslav republic, is also a EU member.

A government official who asked not to be named told Reuters that under questioning Colovic had admitted he was recruited by Croatia’s spy agency in 1999.

“Colovic said he was collecting information about former Yugoslav army officers who fought in Croatia in the 1990s, in exchange for immunity from prosecution there, and that he was paid for that,” the official said.

Croatian authorities deny Colovic ever worked for them.

With polls predicting a close election, Croatian parties have been courting the nationalist vote.

Moves which have infuriated Serbia include rehabilitation of a cleric who supported Croatia’s World War Two-era pro-German government and honouring a man who assassinated a Yugoslav ambassador in the 1970s with a statue.

“This Colovic case was a totally unnecessary escalation in already strained relations with Croatia ... and if it was a tit-for-tat, than it was a rather miserable one,” said Milos Damjanovic, an analyst with the Belgrade-based BIRN Consultancy.

The collapse of Yugoslavia in 1991 plunged the region into a bloodbath that lasted the best part of the 1990s, cost over 130,000 lives, drove around 4 million people from their homes and saw the multinational federation break up into seven successor states.