By Phil Stewart and Yara Bayoumy

WASHINGTON, Aug 9 (Reuters) - A Turkish military officer on a U.S.-based assignment for NATO is seeking asylum in the United States after being recalled by the Turkish government in the wake of last month's failed military coup, U.S. officials told Reuters.

The asylum bid is the first known case involving a Turkish military officer in the United States as Turkey purges military ranks after mutinous soldiers commandeered fighter jets, helicopters and tanks in an unsuccessful attempt to oust President Tayyip Erdogan.

The case has the potential to further strain ties between the United States and Turkey, which is already demanding Washington hand over a U.S.-based Turkish cleric it alleges was responsible for the failed coup.

The two U.S. officials, who spoke to Reuters on condition of anonymity, said the Turkish officer was working at the headquarters of NATO's Allied Command Transformation, located in Norfolk, Virginia. They did not name him or offer his rank.

However, an official at Turkey's embassy in Washington said Turkish Navy Rear Admiral Mustafa Ugurlu had failed to report to authorities after Turkey issued a detention order for him last month.

"On July 22, on that day he left his badges and his ID at the base and after that no one has heard anything from him," the official said, also speaking on condition of anonymity.

The Turkish official said he was unaware of a subsequent asylum request. An April news article on the NATO website identified Ugurlu as the Norfolk-based command's assistant chief of staff for command and control, deployability and sustainability.

The Turkish official said two other lower-level officers had also been called back from the United States to Turkey.

"But there's no detention order for them," the official said. "One of them has gone back, and the other will go back shortly."

MILITARY PURGES

The purges within Turkey's military, which has NATO's second largest armed forces and aspires to membership in the European Union, has resulted in thousands of soldiers being discharged, including around 40 percent of generals.

There are concerns within the Turkish opposition that the restructuring lacks parliamentary oversight and is going too far.

Pentagon spokesman Captain Jeff Davis declined comment, referring questions about Turkish military personnel to Turkey.

The Norfolk mission where the Turkish officer was assigned is the only NATO command in North America, according to its website. It directs Allied Command Transformation's subordinate commands, including the Joint Warfare Center in Norway and the Joint Force Training Center in Poland.

A spokeswoman at the Norfolk-based mission said 26 Turkish military personnel were assigned there, and she praised Turkey's contribution, including hosting U.S. and allies at its Incirlik Air Base, an important staging area for the U.S.-led fight against Islamic State militants in Syria.

"We want to state that Turkey is a valued NATO ally that continues to make important contributions to the fight against ISIL," U.S. Navy Lieutenant Commander Karen Eifert said, declining comment on questions about an asylum request. ISIL is an acronym for Islamic State.

A NATO official, speaking on condition of anonymity, said Turkey's internal reorganization of its military has not had a practical impact on NATO-led commands.

"Turkey has notified NATO about the changeover of a number of Turkish military personnel. There has been no impact on the implementation of NATO-led operations and missions or on the work of NATO commands," the official said, declining comment on any asylum request.

"I would refer you to the Turkish authorities for any further details on their staffing."

U.S. Citizenship and Immigration Services said it could not discuss individual cases, including whether an individual has requested a specific immigration benefit like asylum.

The State Department declined comment.

ANTI-U.S. SENTIMENT RISING

The case comes as Turkey presses Washington to hand over U.S.-based cleric Fethullah Gulen.

Gulen, an ally of Erdogan in the early years after his Islamist-rooted AK Party took power in 2002, has denied any involvement in the coup, which came at a critical time for a NATO state facing Islamist militant attacks from across the border in Syria and an insurgency by Kurdish rebels.

Justice Minister Bekir Bozdag said anti-American feeling among Turks was on the rise and "turning into hatred" and could only be calmed by the United States extraditing Gulen.

Still, the U.S. and Turkish militaries have long had extensive ties, extending beyond the NATO alliance.

One U.S. defense official, speaking on condition of anonymity, estimated there were around 160 Turkish military personnel on assignment in the United States, including those at NATO in Norfolk and others at exchanges at prestigious U.S. military institutions.

Navy Lieutenant Commander Patrick Evans said 123 Turkish military personnel were participating in the U.S. International Military Education and Training Program in the continental United States as of Aug. 9.

Asked how many of those participants had been recalled to Turkey, Evans said: "We are aware of one student currently at the Army War College who received a recall notice to return to Turkey."

The status of the student at the War College, located in Carlisle, Pennsylvania, was not immediately clear. Evans did not comment on any individual cases. (Reporting by Phil Stewart; Aadditional reporting by Julia Hart, Julia Edwards, Jonathan Landay and Arshad Mohammed; Editing by Leslie Adler)

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