The ex-foreign minister of the Khmer Rouge regime and his wife were arrested Monday in the Cambodia capital on charges of crimes against humanity, becoming the latest figures from the 1970s government to await trial before Cambodia's UN-backed genocide tribunal.

Police detained Ieng Sary and his wife, Ieng Thirith, at their residence in Phnom Penh at dawn. Officers later brought them to the tribunal offices, where they were to make an initial appearance before the judges later in the day, said tribunal spokesman Reach Sambath.

"Today Ieng Sary and Ieng Thirith have been arrested in execution of an arrest warrant, delivered by the co-investigating judges, for crimes against humanity and war crimes as regards Ieng Sary and for crimes against humanity concerning Ieng Thirith," a tribunal statement said.

The radical policies of the Communist Khmer Rouge, which held power from 1975 to 1979, are widely blamed for the deaths of some 1.7 million people from starvation, disease, overwork and execution. None of the group's leaders has faced trial yet.

The couple's children declined to comment Monday, hanging up on phone calls made to them.

According to a July 18 filing by the prosecutors to the tribunal's judges, a copy of which was obtained by the Associated Press, Ieng Sary "promoted, instigated, facilitated, encouraged and/or condoned the perpetration of the crimes" when the Khmer Rouge held power.

It said there was evidence of Ieng Sary's participation in crimes included planning, directing and co-ordinating the Khmer Rouge "policies of forcible transfer, forced labour and unlawful killings."

Ieng Sary, thought to be 77, served as a deputy prime minister as well as foreign minister in the Khmer Rouge regime. He has repeatedly denied responsibility for any crimes.

"I have done nothing wrong," Ieng Sary told the Associated Press in October in Bangkok, where he was visiting for a medical checkup.

"I am a gentle person. I believe in good deeds. I even made good deeds to save several people's lives [during the regime]. But let them [the tribunal] find what the truth is," he said without elaborating.

His wife, Ieng Thirith, who is believed to be 75, is accused of participating in "planning, direction, co-ordination and ordering of widespread purges … and unlawful killing or murder of staff members from within the Ministry of Social Affairs," the prosecutors' filing said.

Deeply entwined in the group's leadership, she was the sister-in-law of the late Pol Pot, the top leader of the Khmer Rouge who died in 1998. Her sister, Khieu Ponnary, was Pol Pot's first wife.

Ieng Sary was sentenced to death in absentia in August 1979, eight months after a Vietnam-led resistance movement overthrew the Khmer Rouge regime.

The Khmer Rouge carried on fighting a guerrilla war from the jungle after their ouster, even after signing a peace agreement in 1991. Confined to a dwindling number of strongholds, mostly in border areas, and increasingly reduced to acts of banditry, Ieng Sary became the first member of the inner circle to defect.

In August 1996, he seized control of thousands of Khmer Rouge militants and the gem-rich area they controlled along the Thai border.

A month later, at the request of Prime Minister Hun Sen, the king rewarded Ieng Sary with an amnesty for breaking away from his comrades-in-arms. The amnesty lifted the death sentence against Ieng Sary and granted him immunity from prosecution under a 1994 law outlawing the Khmer Rouge.

The United Nations-backed tribunal was created in 2006 year after seven years of contentious negotiations between the United Nations and Cambodia. Critics have warned that the aging suspects could die before ever seeing a courtroom.

Two others already have been taken into custody. Nuon Chea, the former Khmer Rouge ideologist, and Kaing Guek Eav, also known as Duch, who headed the Khmer Rouge S-21 torture center, were detained earlier in 2007 year on charges of war crimes and crimes against humanity.