PHNOM PENH, September 7, 2008 (AFP) - When they ruled Cambodia, overseeing one of the worst chapters of the 20th century, this probably wasn't how the leaders of the Khmer Rouge envisioned their senior years.

Just 50 metres (yards) away from the UN-backed courtroom where they are scheduled to be tried on war crimes charges later this year, five senior leaders of the regime are locked up in a one-storey yellow bungalow.

In custody are 'Brother Number Two' Nuon Chea, former head of state Khieu Samphan, ex-foreign minister Ieng Sary and his wife Ieng Thirith who was the minister of social affairs, and Kaing Guek Eav, alias Duch, who ran the Khmer Rouge's secret torture centre.

The court, established after nearly a decade of wrangling between Cambodia and the UN, is expected to make the suspects answer charges they helped kill nearly two million people through execution, starvation and forced labour as the Khmer Rouge sought to create an agrarian utopia during its 1975-1979 rule.

For now they reside in cells complete with mosquito net-covered beds, radios and upright toilets -- installed after Nuon Chea, 82, complained about his squat toilet.

Husband and wife Ieng Sary and Ieng Thirith are allowed two-hour visits together daily, but the rest are barred from interacting.

'The guards are making sure that the detainees are not talking to each other unless otherwise authorised by the office of co-investigating judges,' said tribunal spokeswoman Helen Jarvis.

The lawyer for Nuon Chea, the most senior surviving leader after Pol Pot died in 1998, has requested the suspects be allowed to socialise more in custody.

If the bid is successful, it could make for some awkward conversations in pre-trial detention.

Prison chief Duch is expected to testify that Nuon Chea was responsible for purges that claimed tens of thousands of lives and became one of the defining terrors of the regime.

The trial of Duch, 65, is expected to begin in October. These days he likes to sit at his window and watch the guards play chess, said a court official on condition of anonymity.

Nuon Chea has acknowledged the deaths that took place under the regime but denies that he was in a position to stop them.

'I don't know who was responsible (for the deaths),' he told AFP at his home in the former Khmer Rouge stronghold Pailin shortly before his arrest.

As he waits to formally make his case, Nuon Chea pursues his passion for sport.

'Nuon Chea likes to watch football matches. He once asked the jail guards to bring him a program of Euro Cup 2008 matches,' a court official, who declined to be named, said.

After lawyers for Ieng Thirith, known as the regime's 'first lady', argued in her pre-trial appeal that she was not mentally fit to stand trial, the 76-year-old may have read about it the next day.

Each suspect is allowed two hours of television daily and is also given newspapers and books, said Jarvis.

'Ieng Thirith likes watching CNN and BBC and reading the (English-language) Cambodia Daily newspaper,' said the official.

But despite 24-hour medical supervision and daily exercise, the fragile health of the ageing defendants has raised fears that some will not live through their trials.

Khieu Samphan, 77, suffered a stroke while working on a book in May that sent him to hospital for more than two weeks, officials said.

Ieng Sary, 82, has been rushed to hospital several times for a heart condition and blood in his urine -- his lawyers told the court in July that jail could kill him.

'I know that the staff at the detention facility have helped me a lot, but I would like people closer to me to help me better,' Ieng Sary told the court after appealing for release to house arrest until trial.

But Ieng Sary remains in the court's care for now and if donor countries continue to support the trials, the number jailed is more likely to swell than decline.

Prosecutors have said they want to pursue other former Khmer Rouge members, and though five leaders sit in custody for now, there are eight cells in the jailhouse.