THE HAGUE (Reuters) - Appeals judges at the Yugoslav war crimes tribunal upheld on Wednesday the convictions of six Bosnian Croats found guilty of war crimes and crimes against humanity during the 1990s, in the court s last verdict before it closes next month. The International Criminal Tribunal for the former Yugoslavia (ICTY), established by the United Nations in 1993, is due to close when its mandate expires at the end of the year. The six former high-level politicians and defense officials were convicted in 2013 of participating in an  ethnic cleansing  campaign against Bosnian Muslims.  They include Jadranko Prlic, a former defense minister, whose 25 year jail sentence was upheld on Wednesday.  He had been found guilty of being part of a criminal enterprise by the wartime Croatian government of late President Franjo Tudjman, to create an ethnically pure state. Zagreb, which maintained it had  clean hands  in the bloody 1992-95 war in Bosnia, had wanted that finding overturned.      However the appeals chamber concluded that it was not shown that the earlier judges had  misinterpreted relevant evidence  of Tudjman and Zagreb s confirmed Croatia s role in the Bosnian conflict. Several convictions for specific crimes for Prlic and the five others were reversed in the appeal, but president Judge Carmel Agius said  all six remain convicted of numerous and very serious crimes.  