(Adds arrest of wife, questioning) By Ek Madra PHNOM PENH, Nov 12 (Reuters) - Police and security guards from Cambodia's "Killing Fields" tribunal arrested former Khmer Rouge foreign minister Ieng Sary on Monday, the third Pol Pot henchman to be taken into custody by the U.N.-backed court. His wife, Khieu Thirith, another leading member of the Khmer Rouge, was arrested with him, a tribunal spokesman said after the couple had been ferried from their plush Phnom Penh villa in a police convoy with sirens blazing. They would be questioned by investigating judges in an initial appearance later on Monday, he said. The pair would be charged, the spokesman added without specifying the charges or when they would be brought. Ieng Sary became the international face of the ultra-Maoist revolution after its collapse under the weight of a Vietnamese invasion in 1979, spending years at the United Nations defending Pol Pot's legitimacy,. An estimated 1.7 million people were executed or died of torture, disease or starvation under the Khmer Rouge between 1975 and 1979. Ieng Sary has denied having anything to do with the extraordinary privations and brutality during the regime's time in power. He and Khieu Thirith were the third and fourth to be arrested after years of delays since the $56 million tribunal got off the ground in earnest this year. Duch, the former schoolteacher who ran the notorious S-21, or Tuol Sleng, interrogation and torture centre at a former Phnom Penh high school has been charged with crimes against humanity. So has "Brother Number Two" Nuon Chea, who is also accused of war crimes. While Nuon Chea has proclaimed his innocence, Duch, in interviews with Western reporters, has confessed to his role in the mass killings and is expected to be a key witness against other senior regime figures. Pol Pot, "Brother Number One", died in 1998 in the final Khmer Rouge redoubt of Anlong Veng, a jungle-clad mountain on the border with Thailand. In all, prosecutors have so far identified five top suspects. In addition to Ieng Sary, Nuon Chea and Duch, they are widely believed to be former president Khieu Samphan and Meas Muth, a son-in-law of military chief Ta Mok, who died last year. Ieng Sary had been living as a free man in Phnom Penh since he surrendered to the government of Prime Minister Hun Sen -- himself once a Khmer Rouge soldier -- in 1996. Ieng Sary was born in 1924 as Kim Trang but, like many Cambodians, had a penchant for aliases, including Van, Thang and Nenn. He was a member of a group of young Cambodians imbued with socialist and communist zeal while studying on government scholarships in Paris in the 1950s. Many members of the group, which included Pol Pot, Khieu Samphan and Khieu Thirith, went on to become the Khmer Rouge's highest ranking officers. Reports of his ill-health have been frequent in the past few years, including some suggestions he has travelled to Bangkok for heart treatment. (Reporting by Ek Madra; writing by Ed Cropley; editing by Michael Battye and Roger Crabb)
