SARAJEVO -- The Bosnian Serb army confirmed Thursday the Serb-held town of Kupres had fallen after a heavy combined attack by Moslem and Croat forces.


It is the first time since the early days of the 31-month war in Bosnia that Serb forces, which have an overwhelming superiority in tanks and artillery, had lost a major town.


The Bosnian Croat high command said earlier its forces had entered Kupres and taken the entire surrounding area, ending 30 months of Serb occupation.


Forces of the Moslem-led Bosnian government army said they had taken a valley commanding access to Kupres.


United Nations officers said Bosnian Moslem and Croat forces had launched heavy shelling and infantry assaults on Kupres from three directions in a rare display of battlefield cooperation.


Moslem-led Bosnian army troops have been nibbling away at the outer Serb defenses of Kupres, trying to persuade the Bosnian Croats to join them. Kupres had a strong Croat presence before Serbs captured it early in Bosnia's war.


Moslems and Croats began the war as allies against rebel Bosnian Serbs but fell out and fought one another in central and western Bosnia throughout most of 1993.


A rapprochement between Moslems and Croats in early 1994 stopped the killing but had not produced much cooperation on or off the battlefield until this week.