ZAGREB, Croatia-A former Croatian soldier was convicted of murdering three police officials and sentenced to 20 years in prison Monday for an attack that sharply escalated tensions in the early days of the 1991 Serbo-Croat war.

Antun Gudelj fired 30 shots at a car killing a Croatian police chief and two aides because he was angry at their attempts to try to mediate between Serbs and Croats and prevent armed conflict, the state-run news agency HINA quoted judge Damir Krahulec as saying.

Gudelj was manning a checkpoint in the eastern city of Osijek that bordered rival Serb and Croat communities as tensions ran high amid sporadic fighting between the two sides. He claimed he had been told to shoot at any car that approached.

Gudelj, who denied murder, said nobody told him the police chief was coming, despite seeing police lights on the car, and that he should be let through.

Many in Croatia believe Gudelj acted on behalf of Croatian hardliners from the ruling party of the then President Franjo Tudjman, who opposed negotiations with Serb rebels. Tudjman's government denied any involvement in the killings.

Krahulec said Gudelj had been upset because he heard false rumors that Serb rebels had killed his parents. He ordered him to serve 20 years, the maximum penalty at the time of the killing.

Gudelj was jailed for 20 years at a first trial for the killings in 1994 but was pardoned three years later under a wide-ranging amnesty law.

He went to Australia, but Croatia's Constitutional Court ordered a retrial in 2001 and he was extradited a year ago. Gudelj's lawyer, Domagoj Resetar, said he would appeal the ruling.

The war, sparked by local Serbs rebelling against Croatia's independence from Yugoslavia, ended in 1995.