United States immigration officials are seeking to deport at least 150 Bosnians who they believe participated in war crimes and "ethnic cleansing" during the Yugoslav Wars of the 1990s, the New York Times reports.

Officials have identified around 300 immigrants they believe to have been involved wartime atrocities, a number which could rise as high as 600 as more documents and records from Bosnia become available, the Times reports. The Bosnian war left 100,000 dead and displaced two million more from 1992 to 1995.

From the Times:

Evidence developed by immigration officials indicates that perhaps as many as half of the 300 Bosnian suspects in the United States may have played a part in Europe's worst massacre since World War II: the 1995 genocide at Srebrenica, where Bosnian Serb forces executed some 8,000 unarmed Muslim boys and men.

Immigration officials say 64 Balkan immigrants have left the United States, either because they were expelled "through legal proceedings" or because they fled while under investigation. Most cases involve Bosnian Serbs, the Times reports—the majority of the war's atrocities were carried out by Bosnian Serbs seeking to establish their own state and backed by Serbian leader Slobodan Milosevic—although action has apparently also been taken against Bosnian Muslims and Croats.

Just $65,000 was allotted last year for travel and translation expenses for the Immigration and Customs Enforcement's war crimes center, the Times reports. "There's been a lot of covering up of what happened in Bosnia, and a lot of these people who were involved are still walking around," Hamdija Custovic, a Bosnian immigrant and leader of the Congress of North American Bosniaks, said. "Whatever has been done to find these people is not enough. It's tragic."