The countries have reached an initial agreement for five detained Americans to be released in a swap with five detained Iranians and now a flight has left Tehran that is understood to have the prisoners on board.
According to the AP news agency, a US official confirmed that a flight carrying the five prisoners flew out of Tehran on Monday (September 18).
Iranian state media soon after said the flight had left Tehran.
The five prisoners, who include US nationals Siamak Namazi and Emad Sharghi, had all been held on widely criticised spying charges at Tehran’s infamous Evin prison.
Among them is said to be Morad Tahbaz, 67, a British-American conservationist of Iranian descent, who is expected to be released alongside four other Americans under a deal struck by the Biden administration to grant a $6bn (£4.8bn) waiver for international banks to issue frozen Iranian money without incurring sanctions.
As part of the deal, billions of dollars of frozen Iranian assets will be transferred from banks in South Korea to Qatar following months of negotiations.
Last week Iran had moved four of the five Americans in the deal from prison to house arrest. The fifth American was already under house arrest.
Iranian foreign ministry spokesman Nasser Kanaani said: “Fortunately Iran’s frozen assets in South Korea were released and God willing today the assets will start to be fully controlled by the government and the nation.
“On the subject of the prisoner swap, it will happen today and five prisoners, citizens of the Islamic Republic, will be released from the prisons in the US,” he added. “Five imprisoned citizens who were in Iran will be given to the US side.”
He said two of the Iranian prisoners will stay in the US. Washington has yet to publicly comment on the swap.
Here is what we know.
What is the prisoner swap deal?
The US has agreed to free up frozen funds and release prisoners in exchange for the freeing of five American prisoners. International sanctions placed on banks had led to Iran’s access to the money being blocked.
US officials said the money will be sent from South Korea to Qatar, where there will be strict rules on how it can be spent. They said the money will be held in restricted accounts and will be able to be used only for humanitarian reasons and goods, such as medicine and food. Those transactions are currently allowed under American sanctions targeting the Islamic republic over its advancing nuclear programme.
In exchange, Iran has released the five people held as prisoners in the country, who were held under guard at a hotel in Tehran, according to a US-based lawyer acting for one of them.
Who are the US prisoners?
The identities of three of the five are known publicly but the two others are so far being kept under wraps in accordance with their wishes.
The three known are Siamak Namazi, who was detained in 2015 and later sentenced to 10 years in prison on internationally criticised spying charges. Another is Emad Sharghi, a venture capitalist serving a 10-year sentence. The third is Tahbaz, who is of Iranian descent and who was arrested in 2018 and given a 10-year sentence.
Those who have pushed for their release said those named were wrongfully detained and innocent.
Who are the five Iranian prisoners?
On Tuesday (September 12) Iran revealed the names of the five prisoners to be freed by the US as part of the swap deal. Mehrdad Moein Ansari, Kambiz Attar Kashani, Reza Sarhangpour Kafrani, Amin Hasanzadeh and Kaveh Lotfolah Afrasiabi.
Afrasiabi was charged in 2021 with allegedly failing to register as a foreign agent on Iran's behalf, while lobbying US officials on issues including nuclear policy.
Ansari is an Iranian resident of the United Arab Emirates and Germany, who was sentenced to 63 months in prison in 2021 for obtaining equipment that could be used in nuclear weapons and other military equipment.
Hasanzadeh is an Iranian national but permanent US resident, who was charged in 2019 with allegedly stealing engineering plans from his employer to send to Iran.
Kafrani, an Iranian who was living in Montreal, was charged in 2021 with illegally exporting laboratory equipment to Iran.
Kashani is an Iranian-American who was sentenced in February to 30 months in prison for allegedly sending technology to the Iranian government.