Washington D.C. [USA], Dec 7 (ANI): An American graduate student, who had been held for three years in Iran on suspicion of espionage, has been freed and shifted to an American military base in Europe.

Chinese-born Xiyue Wang, a Princeton University PhD student, was conducting research in Tehran when he was arrested there on espionage charges in August 2016.

Wang was sent to Iran's notorious Evin Prison and sentenced to 10 years, CNN reported.

Iran's Foreign Minister Javad Zarif said on Saturday that Wang's release comes as a prisoner swap between the two countries.

In exchange for Wang's release, the US freed Iranian scientist Massoud Soleimani, Zarif said on Twitter, sharing a photo of himself accompanying Soleimani home on an Iranian plane.

Soleimani, an Iranian stem cell scientist, was arrested by the US law enforcement upon landing in Chicago in 2018, according to Iran's state-run Press TV.

Zarif said Soleimani and Wang would be "joining their families shortly."Because the US and Iran do not have diplomatic relations, the Swiss government had provided consular services to Wang and reported back to the State Department.

The White House announced Wang's release in a statement on early Saturday (local time), thanking the Swiss government for their assistance in negotiating with Iran.

"Freeing Americans held captive is of vital importance to my Administration, and we will continue to work hard to bring home all our citizens wrongfully held captive overseas," President Donald Trump said in a statement. (ANI)