The tribunal has been plagued by political wrangling, corruption scandals and inadequate funding over the last few years.
During the closed-door hearing, Verges, 83, said his client's case file containing thousands of pages of documents had not been translated into French.
"French is the official language of the tribunal," Verges said later outside the court.
"I should be capable of knowing what my client is blamed for," he said, adding that the case against his client was "invalid from the start".
The judges then suggested that Khieu Samphan appoint a new lawyer, which angered Verges.
"I have been a lawyer for 50 years. It is the first time I have seen judges ask an accused to change his lawyer," he said. "This is a scandal!"
|The tribunal said it would "issue a warning" to |
Verges for his behaviour [EPA]
The tribunal in a statement later the same day said it would "issue a warning" to Verges for his behaviour leading to the postponement.
said he has known Khieu Samphan since they were both active in left-wing student activities in Paris
in the 1950s.The French lawyer has represented accused terrorists, serial killers, former Nazi officers accused of World War II atrocities and Slobodan Milosevic, the former Yugoslav president.
Khieu Samphan, 76, charged with crimes against humanity and war crimes during the Khmer Rouge's rule between 1975 and 1979, has been in custody since November 19 last year.
He is one of five former Khmer Rouge leaders in custody awaiting trial.
Khieu Samphan, now 76, was the public head of the Khmer Rogue organisation
He was Cambodia's head of state from 1976 until the ousting of the Khmer Rogue by Vietnamese forces in 1979
The son of a judge, he studied for a doctorate in economics at the prestigious Sorbonne in Paris
After surrendering to the government in 1988, he was arrested on November 19, 2007, at a Phnom Penh hospital where he was being treated for a stroke
Has authored two books in which he denies claims of mass killings by the Khmer Rogue and says Pol Pot was responsible for all policies
Up to two million Cambodians are thought to have died or starvation or execution during the Khmer Rouge's brutal four-year rule.The tribunal is expected to hold its first trial later this year.
In its detention order, the tribunal alleged that Khieu Samphan "aided and abetted'' Khmer Rouge government policies that it said were "characterised by murder, extermination, imprisonment, persecution on political grounds and other inhumane acts".
Khieu Samphan himself has never denied the bloodshed suffered by the Cambodian people.
The group's leader, Pol Pot, known as Brother Number One, died in his jungle hide-out in 1998 without ever being brought to justice.
Duch, the former boss of the notorious Tuol Sleng detention centre, and Iengy Sary, Pol Pot's deputy, are both awaiting trial and have both had appeals for bail rejected.
But in an interview in 2003, he urged Cambodians to let go of the past, saying: "We have much more problems to resolve at present and in the future, and we have to forget the past."