SARAJEVO, BOSNIA-HERZEGOVINA — SARAJEVO, Bosnia-Herzegovina -- A plan that would have resulted in the exchange of 6,400 detainees and prisoners of war by all three sides in the Bosnian war has in effect collapsed. New conditions on accounting for missing people that were set by the warring parties caused the plan to be delayed yesterday pending new negotiations. Andre Collomb, a senior official of the International Committee of the Red Cross, said after four hours of talks at Sarajevo airport that there had been no breakthrough in an impasse that has blocked the exchange of about 900 Serbian and Muslim prisoners. Earlier, a similar exchange involving more than 5,000 Muslim and Croatian prisoners was also postponed indefinitely. Officials of the Geneva-based Red Cross body had worked with the United Nations military authorities in Sarajevo on a plan that would have resulted in the release of all detainees and prisoners whose existence has been made known to the Red Cross, and the closure of all but a few of the known detention camps and prisons maintained by the three armies. Red Cross officials had hoped that successful completion of the operation would create new momentum for broader negotiations on an end to the war. When peace talks in Geneva under the auspices of the United Nations and the European Community appeared to be heading toward an agreement to end the war earlier in the fall, the Red Cross resumed negotiations for what it called an "all for all" release of detainees and prisoners. The peace plan collapsed when it was rejected by the Muslim-led Bosnian government, but an accord on the prisoner exchange was reached anyway. By "all for all," the Red Cross proposed that all three sides agree to set free all the people they were holding, without engaging in the bargaining that characterized previous releases. The Bosnian government demanded that Serbian nationalists account for several hundred missing Muslims whom the Bosnian government said have been seized by Serbian forces from their homes in Gorazde, in eastern Bosnia, and at Hadzici, outside Sarajevo, in the spring of 1992. That demand was at the core of the talks at Sarajevo airport yesterday between Bosnian government officials and Serbian representatives.