AMSTERDAM (Reuters) - A Turkish judge on the U.N. court trying crimes from the Yugoslav wars and the Rwandan genocide has been arrested in Turkey in connection with July’s coup attempt, the court’s president said.

Turkey has ignored requests to visit Judge Aydin Sedaf Akay since his arrest on Sept. 21, despite his diplomatic immunity, and this risked violating his judicial independence, court president Theodor Meron told the U.N. General Assembly.

“The U.N. Office of Legal Affairs has requested his release from detention and the cessation of all legal proceedings against him,” Meron said. The arrest is believed to be the first occasion on which a U.N. judge’s immunity has been violated.

At the time of his arrest, Akay was due to hear an appeal in the case against Augustin Ngirabatware, a Rwandan politician who was sentenced in 2012 to 35 years in prison for genocide.

“As a result of his detention, the proceedings have come to a standstill,” Meron said.

Turkish authorities have arrested tens of thousands of people, including teachers, public officials and journalists, since the failed coup, which President Recep Tayyip Erdogan has blamed on supporters of the controversial Muslim cleric Fethullah Gulen.

Critics have accused Erdogan of using the purge to rid himself of opponents and say many with no links to the coup attempt or Gulen’s movement have been caught up in the dragnet.

A former diplomat, Akay was appointed a judge on the tribunal trying perpetrators of the 1994 Rwanda genocide in 2009 and later became a judge on the Mechanism for the International Criminal Tribunals (MICT), its successor.