The top surviving leader of the infamous Khmer Rouge regime was detained Wednesday in Cambodia and is set to appear before a UN-backed court investigating crimes against humanity.

Cambodian security forces and United Nations officials went to the house of Nuon Chea in Pailin, some 400 kilometres north-west of Phnom Penh, and escorted the 82-year-old man known as "Brother Number Two" to the Extraordinary Chambers in the Courts of Cambodia (ECCC).

“Nuon Chea was brought before the office of the co-investigating judge of the ECCC in execution of the arrest warrant. An initial appearance will be held today during which he will be informed of the charges against him,” an official statement released by the court said

A court official said charges could be pressed against Nuon Chea Wednesday and he will remain in the authorities’ custody.

The ECCC is a joint court established by the Cambodian government and the UN to try senior members of the Democratic Kampuchea regime, which led the Asian nation between 1975-79. Nuon Chea is only the second leader of the regime to be brought before the special court, several others being reportedly under investigation.

Many said Nuon Chea is one of the top leaders standing behind the genocide of over a million people and should face trial as soon as possible, as his health is deteriorating rapidly.

The Khmer Rouge leader Pol Pot died in 1998, while the military commander Ta Mok passed away in a hospital last year, leaving Nuon Chea the most senior surviving leader.

Earlier this year, the court charged with crimes against humanity a first man known as Kang Khek Ieu or Duch. He was in charge of the S-21 torture centre during the regime. Duch pointed the finger at Nuon Chea in 1999, saying he is responsible for most of the reprehensible actions between 1975-79.

Nuon Chea, who was in charge of security under the regime, said he is innocent and has nothing to worry about. He surrendered after the movement crumbled almost a decade ago and has been living at his home near the Thai border since then.

After joining the Communist Party, he held numerous positions before being the second-ranking leader of the movement, many considering him “Pol Pot's shadow.”

More than a million people died of torture, forced labor, starvation or were merciless executed. The movement forcibly sent people living in cities to farm lands as part of its drive to turn the country into a power in the agricultural sector.