Iran release of Lebanese man 'positive sign', says Washington

Nizar Zakka, a US resident in his 50s, was arrested in September 2015 during a visit to Iran, where he was convicted the following July.

On Tuesday, Iran freed him in a gesture that comes amid soaring tensions between Tehran and Washington.

"We hope that Mr (Nizar) Zakka's release is a positive sign for American detainees in Iran," a State Department spokesman said. 

Zakka was the head of The Arab ICT Organization, a non-profit that advocates the growth and development of information and communications technology in the Middle East.

Before his arrest, he had been taking part in a conference in Tehran at the invitation of Shahindokht Molaverdi, then vice president for women and family affairs, according to his family.

He was stopped on his way to the airport, his family and lawyer have said.

At the time, Iranian state television said he was accused of "deep ties to the military and intelligence services of the United States".

It broadcast photographs of a man in military uniform it said was of Zakka at a US base.

On Tuesday, Zakka arrived in Lebanon, after his release by Iranian authorities.

He was escorted back to his native country by Lebanon's General Security chief Abbas Ibrahim, who was in Tehran one day earlier, according to the security service.

In a speech at Lebanon's presidential palace, Zakka declined to elaborate on the circumstances behind his arrest but dismissed the case against him.

Agencies contributed to this report.

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