THE HAGUE, Netherlands (AP) _ Austrian police arrested the top Bosnian Serb military commander today on U.N. charges of persecuting Bosnian Croats and Muslims in a bloody 1992 ethnic purge, the Yugoslav war crimes tribunal announced.

Gen. Momir Talic, chief of staff of the Bosnian Serb army, was charged in a sealed indictment with crimes against humanity, ``namely persecutions on political, racial or religious grounds,'' tribunal chief prosecutor Louise Arbour told reporters in The Hague.

The indictment, which also charges former Bosnian Serb deputy prime minister Radislav Brdjanin, accuses the two of ordering, implementing and assisting ``a plan designed to expel the Bosnian Muslim, Bosnian Croat and other non-Serb populations.'' Brdjanin was arrested July 6 and is in the tribunal's custody.

The two men are charged with leading a campaign aimed at driving 100,000 non-Serbs from the Prijedor and Sanski Most regions of northwest Bosnia. Tribunal prosecutors allege that Serb forces under the command of Talic and Brdjanin terrorized Muslims and Croats into fleeing those areas, and that those who didn't leave were driven out by force. Hundreds were killed.

Talic, who was appointed military chief-of-staff in February 1998, was a leading military commander during the Bosnian conflict.

Austrian authorities made the arrest this morning after being tipped off by the tribunal that Talic was attending a conference at the Austrian defense academy on how to merge Bosnian Serb forces and forces from the Muslim-Croat federation into a national army.

Talic's indictment had been kept secret to give authorities a chance to arrest him, the tribunal said. It said it would unseal the indictment and make details public later today or Thursday.

Talic was expected to be extradited to The Hague later today, Austrian Interior Minister Karl Schloegl said.

A spokesman for the Austrian National Defense Academy told the Austria Press Agency that Talic had flown to Vienna on Tuesday aboard a plane of the Organization for Security and Cooperation in Europe and entered the country unhindered. The spokesman said that Talic had been picked by the OSCE for participation in the military seminar.

A high-ranking official in the Bosnian Serb parliament, Dragutin Ilic, denounced the arrest as ``completely immoral.''

``We have said many times we have nothing against public indictments _ they give people a chance to turn themselves in voluntarily to The Hague tribunal in order to prove their innocence,'' Ilic said. But, he added: ``The manner in which a high-ranking official was arrested today is completely immoral and inappropriate. It shames the host country, Austria, which invited him on an official visit.''

Talic would be the highest-ranking Serb military official tried by the tribunal, spokesman Jim Landale said. If convicted, he would face a maximum sentence of life imprisonment.

``Some of the greatest ethnic cleansings were committed in Bosnia directly under Talic's command,'' Amor Masovic, head of the Muslim Commission for Missing Persons, told The Associated Press.

Masovic said his commission discovered the largest number of Bosnia's mass graves in Krajina in northwest Bosnia, an area controlled by Talic during the war.

The graves contained the remains of more than 1,500 Muslims. Another 188 bodies were found in a mass grave in one of Talic's wartime barracks in the village of Laniste, he said.

Masovic said the area had some of the most infamous concentration camps commanded by the Bosnian Serb troops.