Turkey has formally asked the German government to arrest and extradite a top suspect in last year's failed coup attempt following reports suggesting that he has been spotted in Germany.

Foreign Minister Mevlut Cavusoglu said that Turkey submitted a formal note Wednesday demanding fugitive Adil Oksuz's extradition.

Oksuz, accused of being a follower of U.S.-based cleric Fethullah Gulen, is believed to have played a key part in the failed coup. Gulen denies accusations of involvement in the attempt.

The request comes amid souring relations between the two countries. Turkey accuses Germany of providing a safe haven to Kurdish militants and suspects wanted for alleged links to the coup.

Cavusoglu said: "If this person is there, we asked that he be located, taken into custody and returned to Turkey."