Lawyers for former

The chief prosecutor of the International Criminal Court last week alleged Ntaganda had been "coaching potential defence witnesses" as well as interfering with prosecution witnesses after her office reviewed some 450 telephone conversations by the former rebel leader.

"The defence requests an immediate suspension of the proceedings until the information... has been disclosed and more information has been provided about the investigation," Ntaganda's lawyer Stephane Bourgon said in papers filed at the court.

Bourgon said his team wanted to assess how "the fairness" of Ntaganda's trial had been affected, adding that it had not been aware of the prosecution's "secret parallel" investigation into allegations of witness tampering.

"The chilling effect" of the investigation could not be ignored as the defence was not briefed on the scope of the investigation or which witnesses are alleged to have been coached, he said.

Bourgon added that it was unclear whether any members of the defence legal team were implicated, Bourgon said.

"The defence cannot conduct a proper defence without such information," he said in his filing to the court.

Chief prosecutor Fatou Bensouda last week said the review of Ntaganda's telephone conversations showed his "involvement in a broad scheme to pervert the course of justice".

Once dubbed "The Terminator", Ntaganda is on trial for savage ethnic attacks carried out in the Democratic Republic of the Congo by his rebel Patriotic Forces for the Liberation of Congo (FPLC) in 2002-2003.

Ntaganda has denied 18 charges of war crimes and crimes against humanity. But prosecutors say he played a central role in the Ituri conflict in the far northeast of DR Congo which rights groups believe has left some 60,000 dead since 1999.

The trial opened in September 2015 after the former warlord walked into the US embassy in Kigali in 2013 and turned himself in.