Washington calls for release of NASA scientist accused of Gulen links

The United States has called for the immediate release of a NASA scientist arrested in southern Turkey for alleged links to Fethullah Gulen, the US-based Islamic cleric the Turkish government blames for a failed 2016 coup attempt.

Serkan Golge, 36, an American citizen, was arrested at the time of the failed coup.

The US State Department said in a written statement on Thursday that it will continue to follow the case against Golge, insisting it "lacks credible evidence," but welcomed a decision to reduce his sentence.

A court in southern Turkey on Wednesday cut Golge's prison term from seven and a half years to five years and overturned his conviction for membership in a terror organisation.

Tensions between the US and Turkey remain high as Andrew Brunson, an American pastor, continues his detention in Turkey for alleged espionage and terrorism-related offenses.

The spat over Brunson and other issues provoked President Donald Trump to wage sanctions on Turkey as well as double trade tariffs, which pushed the Turkish currency into freefall.

In response, Turkey also doubled tariffs on some US imports including alcohol, cars and tobacco.