A UN expert monitoring sanctions against Libya has left neighbouring Tunisia after being jailed for nearly two months on suspicion of espionage. The UN office in Tunis said Moncef Kartas was released on Tuesday on a provisional basis pending further investigation, and is doing "relatively well". Mr Kartas is a Tunisian-German citizen. The UN and Germany had expressed concern about his arrest and welcomed his release. The German ambassador to the UN, Christoph Heusgen, said on Wednesday that Mr Kartas had left Tunisia but would not say where he went. Tunisian anti-terrorism officials have questioned Mr Kartas's use of a special phone to track air traffic, and said the case concerned his personal activities and not his work for the UN. They said he entered Tunisia on his Tunisian passport, not his UN papers, so he was not entitled to diplomatic immunity. He was jailed on his arrival on March 24. UN co-ordinator Diego Zorrilla, based in Tunis, said Mr Kartas's activities were connected to his UN mandate. Mr Zorrilla said Mr Kartas should be protected by diplomatic immunity even though he had Tunisian citizenship, and that the UN wanted his seized computer and phone returned. Mr Kartas' lawyers said there was no proof of wrongdoing.