THE HAGUE (Reuters) - Lawyers at a U.N. court urged Turkey on Monday to release a judge who is being held in connection with July’s coup attempt, saying his detention was delaying a genocide case.

Judge Aydin Sedaf Akay has been held since September, one of tens of thousands of Turkish officials arrested in a crackdown on people and organizations after the foiled coup in which hundreds died.

Lawyers on both sides of a bid by the defense to reconsider a Rwandan politician’s conviction for genocide said Akay’s absence was holding up the case.

Turkey did not attend a hearing in The Hague on Monday about Akay’s situation and declined to make submissions on his detention, which the court views as illegal because of the diplomatic immunity he enjoys as a U.N. judge.

Turkey was a strong early backer of the international courts set up in the 1990s to try mass crimes from the Yugoslav wars and the Rwandan genocide, but it has become more unilateral under President Recep Tayyip Erdogan.

Akay, a diplomat and long-serving international judge, had been assigned to a panel assembled to determine if new evidence showed Rwandan Augustin Ngirabatware had been wrongfully convicted of genocide and jailed for 35 years.

Ngirabatware’s lawyer, Peter Robinson, rejected the prosecution’s suggestion that Akay might be replaced by a different judge.

“If a state can arrest a judge and the judge has to be replaced, then immunity is restricted,” he said.

“We don’t want judges to have to answer to their states or be fearful of states when they make decisions.”

Robinson said Ngirabatware should be given provisional release in a safe house pending Akay’s return to duty.

Erdogan has blamed the coup on supporters of exiled Muslim cleric Fethullah Gulen, but critics accuse him of using the purge to rid himself of opponents, many with no links to the coup or Gulen’s movement.