ISTANBUL — Iran on Tuesday freed Nizar Zakka, a US permanent resident and Lebanese national, from prison after nearly four years behind bars, handing him over to Lebanese officials who had spent months negotiating his release.
Zakka, who was arrested in Tehran in 2015 and convicted of spying for the US government, arrived in Beirut on Tuesday afternoon and spoke briefly with reporters.
‘‘I will not detail the conditions of my abduction, the fake accusations, and mock trials,’’ he said.
An Iranian court had sentenced Zakka, an information technology expert and Internet freedom advocate, to 10 years in prison on espionage charges — accusations he denies.
‘‘I will always defend the freedom of expression,’’ he said. He thanked Lebanese officials for their efforts to secure his freedom and said his case could de-escalate regional tensions.
The move to free Zakka, 52, was the result of intense negotiations and high-stakes diplomacy between Lebanese and Iranian officials, who said he was released out of respect for the leader of Lebanon’s Hezbollah, a powerful paramilitary group backed by Iran.
Hezbollah, which is part of Lebanon’s coalition government, helped facilitate the diplomacy behind Zakka’s release, Iran’s judiciary spokesman said Tuesday.
‘‘There were no negotiations with any other individual or government,’’ Iran’s semiofficial Fars News Agency quoted an Iranian official as saying Monday, in an apparent nod to Zakka’s status as a US resident.
The Trump administration has not said whether it was involved in the efforts to free Zakka, who was detained in Tehran after attending a conference at the invitation of the Iranian government. Some have interpreted Iran’s gesture as an indirect signal to the United States that it is open to further diplomacy.
‘‘Mr. Zakka was unjustly detained in Iran for almost four years and has endured so much while being held in Iran’s notorious Evin prison,’’ a State Department spokesman said.
The move to release Zakka comes as US-Iran tensions have soared in the region, following President Trump’s decision last year to withdraw from a nuclear agreement between Iran and world powers.
The United States has reimposed harsh sanctions on Iran’s economy and threatened to bolster US military forces in the Persian Gulf region to pressure Iran.
‘‘The United States continues to call on the Iranian regime to release missing and wrongfully detained American citizens,’’ the State Department spokesman said. ‘‘We will continue to do all we can to achieve their immediate and unconditional release.’’
Iran holds a number of dual nationals, including Iranian Americans, as well as Chinese-born US citizen and Princeton scholar, Xiyue Wang. A court in Tehran convicted two Iranian Americans — Baquer Namazi, 81, and his son, Siamak Namazi — of collaborating with the US government in 2016. Their convictions were upheld earlier this year.
US Navy veteran Michael White, 46, was arrested in July after traveling to Iran to visit his girlfriend. In 2016, Washington Post correspondent Jason Rezaian, a US-Iranian dual citizen, was released from an Iranian prison after 544 days of captivity.
Bob Levinson, a former FBI agent, went missing after traveling to the Iranian resort island of Kish in 2007. His whereabouts are unknown.
At the time of his arrest, Zakka, who lived in Washington with his wife, was the secretary general of the Arab-ICT Organization, or IJMA3, a nonprofit group promoting access to information technology in the region.