The head of the Khmer Rouge's largest and most notorious torture center appeared in court Tuesday in the first public session of the long-delayed U.N.-backed tribunal probing the regime's reign of terror in the 1970s.

Kaing Guek Eav, also known as Duch, was escorted by guards into a packed courtroom for a pretrial hearing to seek bail ahead of trials scheduled to begin in 2008.

Duch, 66, who is charged with crimes against humanity, took the witness stand and stood up when asked to tell the court his name. He then brought his palms together in a sign of respect for the five-judge panel beside him.

A presiding judge then read aloud from Duch's case file: "Under his authority, countless abuses were committed, including mass murder, arbitrary detention and torture."

Hundreds of journalists, international observers and Cambodians crowded the tribunal's compound on the outskirts of Phnom Penh to witness the event, which comes almost three decades after the regime fell from power.

"This is historic," said 58-year-old Sin Khor, whose husband and two brothers died during the Khmer Rouge reign. One of her brothers was shot execution-style, she said. "Thirty years have passed. But what happened then remains alive for me."

Two satellite trucks from Cambodian television stations were parked outside the courthouse to carry the proceedings on live television.

The 1975-79 Khmer Rouge regime was blamed for the deaths of some 1.7 million people from starvation, disease, overwork and execution. Many have said they feared the surviving Khmer Rouge leaders might die before being brought to justice. The movement's notorious leader, Pol Pot, died in 1998.

Duch's hearing was held in the tribunal's pretrial chamber, with a live video feed broadcast to the main courtroom that seats 500 people.

He was charged in July with crimes against humanity for his role as the head of the regime's infamous Tuol Sleng prison, also called S-21, in Phnom Penh. Up to 16,000 men, women and children were tortured there from 1975-79 and later taken away to be executed at a site outside the capital known as "the killing fields." Only 14 people are thought to have survived.

According to a transcript of a 1999 government interview obtained by The Associated Press, Duch claimed he was not a "cruel" man, but "an individual with gentle heart caring for justice."

Duch was initially arrested on May 10, 1999 and held without trial until being transferred to the tribunal's custody in July, when he was charged.

When asked the reason for his appeal, Duch rose with palms pressed together and replied, "because I had been detained for more than eight years without trial." A ruling was not expected for several days.

In a detention order in July, the tribunal's investigating judges denied a request by Duch's attorneys to release him. The judges said they have no jurisdiction to determine the legality of Duch's previous detention.

They also argued that his current detention by the tribunal will ensure his appearance at trial and protect him from any violent revenge for the crimes he is accused of.

Tribunal spokesman Peter Foster hailed Tuesday's hearing as "a milestone," saying he hoped it would ease the doubts of critics who feared the tribunal would never materialize.

"It's a big day," he said. "The spotlight will now be on Cambodia."

Duch is one of five top leaders of the Khmer Rouge currently in custody at the tribunal, a former military compound on the outskirts of the capital, Phnom Penh.

His hearing comes one day after former Khmer Rouge head of state Khieu Samphan, 76, was arrested and charged with crimes against humanity and war crimes. Police arrested Khieu Samphan at a Phnom Penh hospital, where he had been undergoing treatment since last week after suffering an apparent stroke.

Last week, authorities arrested Ieng Sary, the Khmer Rouge's ex-foreign minister, and his wife Ieng Thirith, its social affairs minister.Both were charged with crimes against humanity; Ieng Sary was also charged with war crimes.

Former Khmer Rouge ideologist Nuon Chea was detained in September on charges of war crimes and crimes against humanity.