Conservationist Morad Tahbaz among US detainees released and on way to Qatar in first stage of journey to Washington

Five US prisoners detained in Iran, some for nearly a decade, have left the country by plane to Qatar, as part of a controversial prisoner swap involving the unfreezing by the Biden administration of $6bn (£4.8bn) of Iranian oil money.

Tehran and Washington had agreed to swap five prisoners each, including the conservationist Morad Tahbaz, a British-American citizen.

In an elaborate and delicate diplomatic deal, months in the making, the five Americans were taken from hotels in Tehran to a plane bound for Qatar, the first stage in a journey that would take them on flights to Washington.

Qatar has been acting as the mediator for the deal, commencing with the electronic transfer of the Iranian cash to bank accounts in Qatar and Switzerland. The prisoners were allowed to board the plane only after the cash transfer was completed. Apart from Tahbaz, the identity of only two other Americans has been made public.