ANKARA (Reuters) - A U.S. consulate employee in Istanbul was arrested on charges of links to a cleric blamed for last year's failed coup, Turkish media said on Thursday, in a move condemned by Washington as baseless and damaging to ties between the NATO allies.


The U.S. embassy in Ankara said it was deeply disturbed by the arrest of the locally employed staff member and said it appeared that leaked information from Turkish government sources aimed at trying him in the media rather than a court of law.


"Baseless, anonymous allegations against our employees undermine and devalue (the) longstanding partnership" between the United States and Turkey, the embassy said in a statement, dismissing the allegations as "wholly without merit".


Tensions between the two countries have escalated recently over U.S. military support for Kurdish YPG fighters in Syria, considered by Ankara to be an extension of the banned PKK which has waged an insurgency for three decades in southeast Turkey.


Turkey has also pressed, so far in vain, for the United States to extradite U.S.-based cleric Fethullah Gulen, who it blames for the failed coup attempt last year in which more than 240 people were killed. Gulen denies any involvement.


Turkish authorities arrested the consulate employee over his alleged links to Gulen's movement, Turkey's state-owned Anadolu news agency reported.

Anadolu identified the man as a Turkish citizen, and said he was arrested late Wednesday on charges of espionage and attempts to damage the constitutional order and Turkey’s government.

Since the coup attempt in July last year, more than 50,000 people have been jailed pending trial over links to Gulen, while 150,000 people have been sacked or suspended from jobs in the public and private sectors.

Rights groups and some of Turkey's Western allies have voiced concern about the crackdown, fearing the government is using the coup as a pretext to quash dissent.

The government says only such a purge could neutralize the threat represented by Gulen's network, which it says deeply infiltrated institutions such as the army, schools and courts.

Tensions with the United States have been further fueled by the indictment last month by a U.S. court of Turkey's former economy minister Zafer Caglayan.

Caglayan and the ex-head of a state-owned Turkish bank were charged with conspiring to violate U.S. sanctions on Iran by illegally moving hundreds of millions of dollars through the U.S. financial system on Tehran’s behalf.

Turkey says its former economy minister acted within international law and that charges against him amounted to a coup attempt through American courts.

(Reporting by David Dolan; Writing by Ece Toksabay; Editing by Dominic Evans)