Robert Petit, who will resign as the UN’s prosecutor at the Khmer Rouge tribunal in September, told media Wednesday his decision was not based on an ongoing division with his Cambodian counterpart over further indictments of former regime leaders.

His resignation was “a fully private matter,” he told reporters, and “unrelated to my professional responsibility at the court.”

Petit has argued that six more suspects could be charged by the UN-back tribunal beyond the five former leaders of the regime already in custody. Cambodian prosecutor Chea Leang has said she worries more indictments could destabilize the country.

Concerns that his resignation, announced Tuesday, was a result of that disagreement were “unfounded,” he said.

Petit has worked at the UN-backed tribunal, which is undertaking its first trial, of prison chief Duch, for three years. His impending departure has stirred some concerns that the tribunal, which was originally to last three years, could see further delays.

Petit said his resignation “will not impact the whole process of the tribunal.”

His proposal to indict more leaders met with opposition from the Cambodian prosecutor, Chea Leang, as well as Prime Minister Hun Sen. The Pre-Trial Chamber of the court has not decided on the contentious proposal.

“I regretted that he is leaving,” Chea Leang said, adding there was no conflict between the two.