Cambodia's head of state, King Norodom Sihanouk, has said he's ready to renounce his royal and constitutional immunity and appear voluntarily before any tribunal investigating crimes committed by former Khmer Rouge leaders.

In a statement issued from Beijing where he is receiving medical treatment, King Sihanouk said he'd accept any verdict, even if it meant going to prison.

The King, who's made the offer before, was briefly head of state during the Khmer Rouge's years in power in the late nineteen-seventies, when an estimated one-million-seven-hundred-thousand people died.

United Nations legal experts are due to recommend later this month whether there's sufficient evidence to bring prosecutions.