A Turkish rear admiral on a NATO assignment in the US has sought asylum in the country after Ankara sought his detention following the failed July 15 coup, state-run media said Wednesday.

Turkish authorities have ousted thousands of military personnel including nearly half its generals and admirals since a rogue military faction tried to oust President Recep Tayyip Erdogan from power.

Rear Admiral Mustafa Zeki Ugurlu is the subject of a detention order in Turkey and has been expelled from the armed forces, the Anadolu news agency reported.

He has requested asylum from US authorities, it added, without giving its source. He had been stationed at NATO's Allied Command Transformation in Norfolk, Virginia, the news agency said.

Ugurlu had not been heard from since July 22 when he left the base, Anadolu said.

Izmir's chief prosecutor Okan Bato told Anadolu he was not able to get a statement from Ugurlu after seeking the prosecution of two admirals from the chief of staff.

NATO said on Wednesday that Turkey's membership of the military alliance was "not in question", despite the tumult in the country.

Anadolu did not say whether the United States had accepted Ugurlu's claim, believed to be the first of its kind since July 15, which comes at a time of strained relations between Washington and Ankara.

The Turkish government has repeatedly pressed Washington to extradite Pennsylvania-based preacher Fethullah Gulen whom it blames for the coup bid, warning Washington that relations could suffer over the issue.

"If the US does not deliver (Gulen), they will sacrifice relations with Turkey for the sake of a terrorist," Justice Minister Bekir Bozdag told reporters during a televised briefing in the capital Ankara on Tuesday.

Gulen strongly denies the accusations and his lawyer on Friday said Ankara had failed to provide "a scintilla" of proof to support its claims.

Since July 15, tens of thousands of people from the military, judiciary, civil service and education establishment suspected of links with Gulen and his Islamic movement have been sacked or detained.