The pair are being tried at a special United Nations backed court

Chea and Samphan have already been found guilty of genocide

The regime forced people to leave cities and towns to work in the fields

The Khmer Rouge ruled Cambodia between 1975 and 1979 killing two million

Two of Pol Pot's senior leaders during the Khmer Rouge purges in Cambodia appeared in a United Nations backed court yesterday facing charges of mass murder, forced marriage and rape.

Nuon Chea, 88, known as 'Brother Number Two', and ex-head of state Khieu Samphan, 83, have already been given life sentences after a separate trial at the same court in August for crimes against humanity.

That ruling saw them become the first top figures to be jailed from a regime responsible for the deaths of up to two million Cambodians from 1975-1979.

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Former Khmer Rouge leaders Khieu Samphan, left and Nuon Chea, right, are on trial in Cambodia in a special UN backed court facing charges of mass murder and rape over their time in power between 1975 and 1979

The Khmer Rouge leader Pol Pot, right, was known as 'Brother Number One', his deputy Nuon Chea, also known as 'Brother Number Two', centre, and Khieu Samphan, left have already been found guilty of genocide

The second trial, which opened in July, got under way Friday with judge Nil Nonn reading out the charges of genocide, crimes against humanity and war crimes.

Nuon Chea, wearing his trademark black sunglasses, and Khieu Samphan sat in court alongside their defence teams as around 300 survivors of the regime protested outside, demanding monetary compensation for their suffering.

The complex case against the pair was split into a series of smaller trials in 2011 to get a faster verdict given the vast number of accusations and their advanced age.

Both men have appealed their August convictions, which followed a two-year trial focused on the forced evacuation of around two million Cambodians from Phnom Penh into rural labour camps and murders at one execution site.

The second trial, broader in scope than the first, is viewed as an opportunity for many other victims of the regime to seek redress.

Prosecutor Chea Leang told the court in his opening statement: 'The accused will now face trial for the biggest crimes for which they have been indicted This court cannot be closed until justice is done for the victims of these crimes.'

The testimony by the prosecution's first witness, originally scheduled for Monday, has been postponed until October 27.

Khieu Samphan, pictured, was the Khmer Rouge's former head of state between 1975 and their fall in 1979

It is estimated that Nuon Chea and his fellow leaders were responsible for the murder of two million people

Pol Pot, pictured, ruled Cambodia, which he named Democratic Kampuchea, between 1975 and 1979

THE BRUTAL TERROR OF LIFE UNDER THE KHMER ROUGE The Khmer Rouge, the communist ruling party in Cambodia between 1975 and 1979, was responsible for the deaths of almost two million people, through executions, torture and starvation. Its leader, Pol Pot, was determined for society to be transformed into classless agricultural communism – at any cost. City dwellers were marched into the countryside to become farmers in labour camps, with those refusing to move shot dead and their homes burned to the ground. Factories, schools, banks and even hospitals were shut down and the population denied medicine. Many died through starvation – after all, most people from cities had no idea how to fend for themselves in the countryside and farmers were often too terrified to help them adapt. Some died through exhaustion, because the regime severely overworked those tending the land. Many were tortured and executed for being ‘enemies of the regime’. Anyone with links to the former Cambodian government, filmmakers, writers and indeed anyone deemed to be intellectual deserved to be put to death in the eyes of Pot. Even simply owning a pair of glasses could prove fatal, because as far as the regime was concerned, it meant that books were being read instead of hard labour being carried out. Religion was outlawed, so Christians, Muslims and Buddhists were also executed in huge numbers. Advertisement

The mass killings of an estimated 100,000 to 500,000 ethnic Cham Muslims and 20,000 Vietnamese form the basis of the genocide charges against the pair.

Before these charges were filed, the treatment of the minority Muslim group and Vietnamese community was rarely discussed.

Seth Maly, a 64-year-old Cham labour camp survivor who lost 100 of her relatives, including her two daughters, parents and five siblings said: 'The ways in which the Khmer Rouge mistreated us is too heinous to describe in words. Their goal was to exterminate our race.'

Nuon Chea and Khieu Samphan also face charges of crimes against humanity and war crimes in the second trial - for the deaths of up to two million Cambodians through starvation, overwork or execution during the communist regime.

Most of these deaths do not fall under the charge of genocide, which is defined by the United Nations as 'acts committed with intent to destroy, in whole or in part, a national, ethnic, racial or religious group'.

Anne Heindel, an adviser to the Documentation Center of Cambodia which researches the country's bloody history.'Without a second trial, there would be an enormous gap in the legal record about crimes that defined the experience of - and still traumatise - regime survivors.'

Led by 'Brother Number One' Pol Pot, who died in 1998, the Khmer Rouge dismantled Cambodian society in a bid to create an agrarian utopia.

The hearings will also provide the first forum for justice for tens of thousands of husbands and wives forced to marry, often in mass ceremonies, as part of a Khmer Rouge plan to boost the population.

The rape charges refer to rape within the forced marriages.

A court spokesman has estimated the trial may go on until 2016, with hearings covering crimes committed at Khmer Rouge labour camps and prisons including the notorious Tuol Sleng, also known as S-21.

In its historic debut trial, the court in 2010 sentenced former Tuol Sleng prison chief Kaing Guek Eav to 30 years in prison - later increased to life on appeal - for overseeing the deaths of 15,000 people.

Since the fall of the Khmer Rouge in 1979, researchers have found mass graves containing thousands of victims of the regime's violence after they cleared towns and cities murdering suspected intellectuals

The regime routinely shot people wearing glasses in the head because they were deemed 'intellectuals' and were more interested in reading books rather than working hard in the fields