“Glad that Professor Massoud Soleimani and Mr. Xiyue Wang will be joining their families shortly,” Iranian Foreign Minister Mohammad Javad Zarif wrote on Twitter.
“Many thanks to all engaged, particularly the Swiss government,” wrote Zarif, who also posted pictures of himself with Soleimani talking on board an Iranian plane.
Separately, US President Donald Trump said in a statement issued by the White House on Saturday that Wang was “returning to the United States”.
“Mr. Wang had been held under the pretense of espionage since August 2016,” Trump said. “We thank our Swiss partners for their assistance in negotiating Mr. Wang’s release with Iran.”
“We’re hopeful this will lead us to further success with Iran,” he told reporters.
In a statement, Hua Qu, Wang’s wife, said the “family is complete once again.”
“We are thankful to everyone who helped make this happen,” she said.
Wang was sentenced to 10 years in prison in Iran for allegedly “infiltrating” the country and sending confidential material abroad. His family and Princeton University strongly denied the claims.
Soleimani – who works in stem cell research, haematology and regenerative medicine – was arrested by US authorities on charges he had violated trade sanctions by trying to have biological material brought to Iran.
The scientist and his lawyers maintained his innocence, saying he seized on a former student’s plans to travel from the US to Iran in September 2016 as a chance to get recombinant proteins used in his research for a fraction of the price he would pay at home.
Tensions have been high between the US and Iran since Trump unilaterally withdrew his country from Tehran’s nuclear deal with world powers in May 2018.
Since then, the US has imposed harsh sanctions on Iran’s economy. There have also been a series of attacks across the Middle East that Washington blames on Tehran over Iranian denials.