A Lebanese man with permanent USA residency who had been imprisoned in Iran for years on charges of espionage said Tuesday that he was subjected to "kidnapping, arbitrary detention and a show trial", adding that his release served to de-escalate tensions between the us and Iran.
Iran's Sobh-e-No newspaper reported that Nasrallah played a key role in persuading Iranian officials to release Nizar Zakka.
Meanwhile, head of the Lebanese General Security, General Abbas Ibrahim left Beirut on Sunday heading for Tehran to complete efforts to release Zakka.
Zakka, a computer scientist and Internet freedom advocate, was detained in Tehran after attending a conference at the invitation of the Iranian government.
Officials of the Foreign Ministry in Beirut were quoted as saying on June 4 that Iran had agreed to grant amnesty to Lebanese citizen Zakka, an information technology expert, it detained in 2015 for "collaborating against the state", according to Reuters.
He denied the charges, while Iranian media have described him as a US spy.
Relatives of Zakka were also present at the presidential palace.
Zakka's release comes amid heightened tensions between Iran and the USA after America's withdrawal from Tehran's nuclear deal with world powers.
But Iranian newspaper Sobh-e No asserted that his release was secured only following the intervention of Hassan Nasrallah, the leader of the Iran-backed Lebanese militant group Hezbollah.
Zakka, who also holds US residency and was sentenced in 2016 to 10 years in prison and a $4.2 million fine for "collaborating against the state".
State TV later quoted an anonymous source as saying Zakka would be released on Tuesday afternoon and will be allowed to leave Tehran.
Iran holds a number of dual nationals, including Iranian Americans, as well as Chinese-born US citizen and Princeton scholar, Xiyue Wang.
A spokesman for Iran's judiciary said Zakka's release was "a totally judicial process without any political stances or (prisoner) exchange being considered". Iranian media has described him as a United States spy.
Sarah Fallah, a Lebanese lawyer who represented Zakka, told HRW in March 2016 that Iranian authorities refused to let her visit her client.
Zakka's IJMA3 organization had received at least $730,000 in contracts and grants since 2009 from both the State Department and USAID, the lead American government agency fighting poverty and promoting democracy across the world.
"This is in no way approved by the government", Molaverdi said.
On May 11, Mr Aoun handed over a written letter to Mr Firouznia to be delivered to Iranian President Hassan Rouhani, repeating Lebanon's request for Mr Zakka to be freed at the end of Ramadan, the source said.