Americans detained for years in Iran have arrived in the US after being freed as part of a deal that saw US President Joe Biden agree to the release of nearly six billion dollars (£4.84 billion) in frozen Iranian assets.

Morad Tahbaz, a British-American conservationist of Iranian descent, is one of the prisoners.

The successful negotiations for the Americans’ freedom brought Mr Biden profuse thanks from their families but heat from Republican presidential rivals and other opponents for the monetary arrangement with one of America’s top adversaries.

“Today, five innocent Americans who were imprisoned in Iran are finally coming home,” Mr Biden said in a statement released as the plane carrying the group from Tehran landed in Doha, Qatar, on Monday.

In the early hours of Tuesday, a plane carrying the Americans landed in the United States, according to a US official, who spoke on the condition of anonymity because he was not authorised to discuss the matter publicly.

US secretary of state Antony Blinken at a news conference where he said five Americans jailed for years in Iran had been freed
US secretary of state Antony Blinken at a news conference where he said five Americans jailed for years in Iran had been freed (Craig Ruttle/AP)

Iran’s hard-line President Ebrahim Raisi, on hand for the United Nations General Assembly in New York, suggested the exchange could be “a step in the direction of a humanitarian action between us and America”.

“It can definitely help in building trust,” Mr Raisi told journalists.

However, tensions are almost certain to remain high between the US and Iran, which are locked in disputes over Tehran’s nuclear programme and other matters.

Iran says the programme is peaceful but now enriches uranium closer than ever to weapons-grade levels.

The prisoner release unfolded amid a major American military buildup in the Persian Gulf, with the possibility of US troops boarding and guarding commercial ships in the Strait of Hormuz, through which 20% of all oil shipments pass.

After the plane slowed to a stop in Doha, three of the prisoners — Siamak Namazi, Emad Sharghi and Mr Tahbaz — emerged.

They hugged the US ambassador to Qatar, Timmy Davis, and others.

The three then threw their arms over each other’s shoulders and walked off towards the airport.

Family members embrace freed American Emad Shargi
Family members embrace freed American Emad Shargi (Jonathan Ernst/AP)

In a statement issued on his behalf, Mr Namazi said: “I would not be free today if it wasn’t for all of you who didn’t allow the world to forget me.

“Thank you for being my voice when I could not speak for myself and for making sure I was heard when I mustered the strength to scream from behind the impenetrable walls of Evin Prison.”

The US did not immediately identify the other two freed Americans.

All were released in exchange for five Iranians in US custody and for the deal over the frozen Iranian assets owed by South Korea.

The Biden administration said the five freed Iranians pose no threat to US national security.

Two of the imprisoned Americans’ family members, Effie Namazi and Vida Tahbaz, who had been under travel bans in Iran, were also on the plane.

Iranian foreign ministry spokesman Nasser Kanaani said two of the Iranian prisoners will stay in the US.

Meanwhile, Nour News, a website believed to be close to Iran’s security apparatus, said two of the Iranian prisoners were in Doha for the swap.

Family members greet Siamak Namazi, Morad Tahbaz and Emad Shargi
Family members greet Siamak Namazi, Morad Tahbaz and Emad Shargi (Jonathan Ernst/AP)

Nour News identified the two in Doha as Mehrdad Ansari, an Iranian sentenced by the US to 63 months in prison in 2021 for obtaining equipment that could be used in missiles, electronic warfare, nuclear weapons and other military gear, and Reza Sarhangpour Kafrani, an Iranian charged in 2021 over allegedly unlawfully exporting laboratory equipment to Iran.

The 5.9 billion US dollars (£4.76 billion) in cash released to Iran represents money South Korea owed Iran — but had not yet paid — for oil bought before the US imposed sanctions on such transactions in 2019.

The US maintains that, once in Qatar, the money will be held in restricted accounts to be used only for humanitarian goods, such as medicine and food.

Those transactions are currently allowed under American sanctions targeting the Islamic Republic over its advancing nuclear programme.

Iranian government officials have largely concurred, though some hard-liners have insisted, without evidence, that there would be no restrictions on how Tehran spends the money.

The deal has already opened up Mr Biden to fresh criticism from Republicans and others, who say the administration is helping to boost the Iranian economy at a time when Iran poses a growing threat to American troops and Middle East allies.

That could have implications in his re-election campaign.

Former US president Donald Trump, currently the lead Republican challenger in that race, called it an “absolutely ridiculous” deal on his Truth Social social media site.

Senate minority leader Mitch McConnell accused Mr Biden of “rewarding and incentivising Tehran’s bad behaviour”.

Iran's President Ebrahim Raisi meets United Nations secretary-general Antonio Guterres at the UN headquarters on Monday
Iran’s President Ebrahim Raisi meets United Nations secretary-general Antonio Guterres at the UN headquarters on Monday (Craig Ruttle/AP)

Mr Biden held what the White House described as an emotional phone call with the families of the freed Americans after their release.

In his statement, Mr Biden demanded more information on what happened to Bob Levinson, an American who went missing years ago.

The Biden administration also announced fresh sanctions on former Iranian president Mahmoud Ahmadinejad and the Iranian ministry of intelligence.

The US government, the prisoners’ families and activists have denounced the charges against the five Americans as baseless.

The Americans include Mr Namazi, who was detained in 2015 and later sentenced to 10 years in prison on spying charges, Mr Sharghi, a venture capitalist sentenced to 10 years, and Mr Tahbaz, who was arrested in 2018 and also got a 10-year sentence.

In a statement, Mr Sharghi’s sister Neda said she “can’t wait to hug my brother and never let him go”.

“This is my brother, not an abstract policy,” she added.

“We are talking about human lives. There is nothing partisan about saving the lives of innocent Americans and today should be a moment of American unity as we welcome them home.”

Iran and the US have a history of prisoner swaps dating back to the 1979 US embassy takeover and hostage crisis following the Islamic Revolution.