Cambodia's U.N.-backed genocide tribunal arrested the former Khmer Rouge head of state and charged him Monday with crimes against humanity and war crimes, a spokesman said.

Khieu Samphan was the last of five senior officials of the brutal regime to be taken in custody ahead of a long-delayed genocide trial.

Police arrested Khieu Samphan, 76, at a Phnom Penh hospital where he had been undergoing treatment since Nov. 14 after a stroke. Officers held his arms to support him as they led him to a police car, which sped away in a heavily guarded convoy to the tribunal's offices.