Croatia's Supreme Court said Friday it upheld the conviction of a fugitive lawmaker for war crimes against Serb civilians in the 1991-1995 war but cut two years off his sentence.

The jail term of Branimir Glavas for abduction, torture and murder was reduced from 10 to eight years after it was found he had initially been sentenced for two criminal acts that should have been joined as one, the court said in a statement.

The right-wing lawmaker, 53, is the most senior Croatian politician to be convicted by a local court for war crimes during the conflict sparked by Croatia's proclamation of independence from the former Yugoslavia in 1991.

He is living in neighbouring Bosnia-Hercegovina where he fled immediately after being sentenced in 2009 as he holds both Bosnian and Croatian passports.

While confirming the conviction, the Supreme Court said it was "legally correct" that he be sentenced for "one criminal act of war crimes against civilians" and not for two as he had initially been by a Zagreb court.

"The number of victims of war crimes does not influence the number of criminal acts that a perpetrator makes," it said.

"So there were no legal grounds that the verdict of Branimir Glavas be divided into two separate criminal acts of war crimes against civilians."

Glavas was sentenced for ordering the 1991 abduction, torture and murder of at least 10 Serbs by a special unit in the eastern Croatian town of Osijek, where he was defence chief.

He claimed his innocence Friday and labeled his conviction "political".

"They have sentenced an innocent man. It is a political verdict," he told the state HINA news agency from Bosnia.

"If the Supreme Court judges have undoubtedly established that I'm guilty for brutal war crimes, then the tribunal should have sentenced me to a maximum 20-year jail term," he said.

Glavas escaped to Bosnia to avoid prison since the two countries did not have an extradition agreement.

But earlier this year Sarajevo and Zagreb reached a deal by which convicts can serve a jail term in either country once their verdict becomes final.

This means that once Croatia's judiciary files a request to its Bosnian counterparts, Glavas would have to be detained and serve his sentence either in Bosnia or in Croatia.

Glavas' lawyer, Ante Madunic, said he would refer the Supreme Court verdict to the Constitutional Court.

Five other people tried with Glavas were sentenced to between five and eight years behind bars for carrying out eight of the executions on his orders.

The Supreme Court said Friday it had also reduced their sentences.

Croatia's ability to handle war crimes involving its own nationals is closely monitored by the European Union, which Zagreb hopes to join by 2012.