The United Nations war crimes tribunal has reduced to 40 years the life prison term of a former Bosnian Serb mayor convicted of overseeing detention camps for Croats and Muslims.

The appeals chamber of the Hague-based court Wednesday said Milomir Stakic's conviction would stand, but cut his prison term.

The court said the lower judge had made errors in the sentencing procedure, but called the impact of the problem limited.

In 2003, Stakic was the first person to be sentenced to life in prison by the tribunal.

He was convicted of helping to set up three prison camps near the town of Prijedor, in northwestern Bosnia-Herzegovina where he was mayor.  The court acquitted him of genocide charges.

More than 20,000 Bosnian Muslims and Croats were driven from their homes in Prijedor, and more than 15,000 were killed.

Some information for this report was provided by AP.