Topuz is accused of having links to US-based Turkish Muslim scholar Gulen, whom Ankara blames for 2016 coup attempt.
The trial of a Turkish employee of the US consulate in Istanbul has started after he was charged with espionage and attempting to overthrow the Turkish government in one of several cases heightening tensions between the United States and its NATO ally.
Metin Topuz, a Turkish citizen and liaison with the US Drug Enforcement Administration, was arrested in 2017 and has been accused of having ties with US-based preacher Fethullah Gulen, who the Turkish Government said ordered a failed coup to topple President Recep Tayyip Erdogan in 2016.
The trial commence as diplomatic relations between the US and Turkey have worsened with disagreements over the war in Syria, Turkey’s purchase of missiles from Russia and the refusal of US to extradite Gulen.
The first hearing of Topuz’s trial in Caglayan court in Istanbul is expected to last three days. He faces life imprisonment if found guilty of spying and plotting to overthrow the government.
The US embassy has called the accusations “wholly without merit”.
US officials said freeing “unjustly detained” Turkish nationals on their staff was a priority, as was the case of NASA scientist Serkan Golge, a dual US-Turkish national jailed on “terror charges”.
Another Istanbul local consulate staffer, Mete Canturk, is under house arrest and facing similar charges to Topuz.
A judge in January convicted Hamza Ulucay, a former local employee of the US consulate in Adana, southern Turkey, of helping outlawed Kurdish fighters. He was released taking into account the time already served in jail.