BELGRADE (Reuters) - Serbia has extradited to Turkey a Kurdish political activist who had been seeking asylum, a police official said on Tuesday, defying a recommendation by the United Nations  Committee against Torture. Cevdet Ayaz requested asylum in Serbia earlier this year after fleeing Turkey, where he had been sentenced to 15 years in prison over alleged activities against the constitution, the Belgrade-based N1 TV quoted his lawyer Ana Trkulja as saying. It also quoted her as saying that Ayaz had been extradited to Turkey on Monday and that his brother had been asked to contact a police station in Istanbul where he was being held.  The U.N. Committee against Torture (UNCAT) issued a recommendation on Dec. 18 urging Belgrade to refrain from extraditing Ayaz. The Serbian police official, speaking on condition of anonymity, said Serbian courts had ruled that all preconditions for the extradition had been met and that Justice Minister Nela Kuburovic had acted accordingly.  The motion by the U.N. came after that (decision) ... The police only performed the extradition procedure,  the official said. Officials at Serbia s Justice Ministry, which approved Ayaz s extradition, were not immediately available for comment on the case. On Monday UNCAT chairman Jens Modvig warned Serbia, a candidate for European Union membership, to adhere to its international obligations.  Serbia is in the process of extraditing Mr. Ayaz to Turkey ... Serbia, please be aware of your UNCAT obligations,  Modvig wrote on his Twitter account.  Rights groups accuse Turkish President Tayyip Erdogan of using a state of emergency declared after the 2016 coup attempt to quash decades-long Kurdish dissent and political opposition. Turkey, which is also a candidate for EU membership, denies using torture. Serbia, the legal successor to the now-defunct Yugoslavia, has ratified the U.N. convention against torture, which came into force in 1987.  Serbia s President Aleksandar Vucic has sought to boost trade ties with Turkey, and Erdogan visited Belgrade in October. 