ISTANBUL (Reuters) - Turkish prosecutors have prepared the charge sheet against a local employee of the U.S. consulate who was arrested over alleged links to the network of U.S.-based cleric Fethullah Gulen, Demiroren News Agency (DHA) reported.

Gulen is accused by Ankara of orchestrating a coup attempt in 2016, in which he denies all involvement.

Consulate worker Metin Topuz’s arrest in October 2017 added to existing tensions between the United States and Turkey, and led to a months-long suspension of bilateral visa services.

Relations between the two NATO allies have been strained over U.S. support for Kurdish fighters in northern Syria, Turkey’s plan to buy a Russian missile defence system, and the U.S. jailing of an executive at a Turkish state bank in an Iran sanctions-busting case.

Topuz is in jail along with two other local consulate employees, as is a Turkish-U.S. national and former NASA scientist who faces terrorism charges. Washington wants all of them to be released.

DHA quoted from Topuz’s 78-page indictment, which stated that he had very close contact with police officers suspected of playing a role in the coup attempt. The news agency said the document listed President Tayyip Erdogan and former Prime Minister Binali Yildirim, amongst others, as complainants.

Under Turkish law, a judge would now decide if Topuz’s case should proceed to trial.

The prosecutor’s office could not immediately be reached for comment on Saturday.

Ankara has repeatedly demanded that the United States extradite Gulen to Turkey. The cleric has lived in self-imposed exile since 1999.

Turkey has detained 160,000 people and dismissed nearly the same number of civil servants over suspected links to the coup attempt, according to the U.N. human rights office.

There was some easing of U.S.-Turkish tensions late last year when an Ankara court freed a U.S. pastor who had been detained for two years over accusations of links to Kurdish militants and supporters of Gulen.