Turkey accused Athens of protecting “terrorists” after a Greek court granted asylum to a Turkish serviceman who Ankara claims was involved in the country’s failed coup, threatening to increase simmering tension between the two NATO countries.

The Turkish foreign ministry stated on Thursday that Greece "protects and shelters putschists” and the ruling went against international law.

"We hope that the Greek judiciary will refrain from repeating the same mistakes," the statement added.

The ruling by Greece’s top administrative court on Wednesday is expected to apply to seven other officers who fled Turkey in a helicopter alongside the serviceman on July 16, 2016, as the coup was being thwarted after it was launched the night before.

A judicial source said an appeal by the Greek government against granting asylum was rejected.

The Turkish soldiers deny they took part in the coup and say they are scared for their lives.

Ankara has filed extradition requests for the men but Greek courts have refused to return them, saying they do not believe the men would receive fair trials in Turkey.

Turkish EU Minister Omer Celik tweeted that the Greek legal system “ruled to protect the terrorists” and it was the “most embarrasing (sic) ruling possible for any country.”