Two senior Khmer Rouge leaders were sentenced to life imprisonment for genocide for their part in the regime`s 1975-1979 reign of terror, a UN-backed war crimes court said Friday in a historic ruling. "The chamber... finds that Nuon Chea is responsible for all the crimes," presiding judge Nil Nonn told the court. "This includes the case of genocide" against Cham Muslims and ethnic Vietnamese. "The chamber sentenced Nuon Chea to life imprisonment," he added. Head of state Khieu Samphan was found guilty of genocide against ethnic Vietnamese and would also receive a life term, he added.