According to Iranian government sources, the 400 million debt the UK paid to Iran was still not reached by the time of the release of British-Iranian dual nationals Nazanin Zaghari-Ratcliffe and Anoosheh Ashoori.
The money was blocked in Oman and the problem was not with the UK government, according to a senior Iranian government source. One report said only 1 m had been transferred to Tehran.
The UK made it a condition that the money would only be used for humanitarian purposes, but this condition was not repeated in a statement by the Iranian government at the time.
Oman acted as a mediator in the talks that led to the transfer of the longstanding debt at the time of the release of the two UK detainees on 17 March. Both sides maintained that the payment of the 40 year-old debt and the release were not linked, but many said this was a diplomatic fiction.
The UK refused to comment directly on Iranian media reports, but pointed out previous UK and Iranian government statements that the debt had been paid with accrued interest.
Mahmoud Abbaszadeh Meshkini, the Iranian parliament spokesman spokesman for the national security and foreign policy commission, said the money was blocked, and was asked to speak to the Iranian newspaper Entekhab, Mahmoud Abbaszadeh Meshkini. He said that we are working with the countries of the region in some way, and some neighbouring countries are consulting and mediating in order to receive our demands.
He said it was important that the blocked money was released.
The extent of the hold up is not clear and it is not known whether it is due to a banking problem in Oman or another issue, such as the limits on the use of money by the British.
The Foreign Office said that the payment was in full compliance with UK and international sanctions and all legal obligations. The Iranian government also said at the time that it had full authority and freedom to use its money, because it believed Iran has not kept its side of the negotiated deal that should have allowed a third British-Iranian, Morad Tabhaz, indefinite leave at his family home in Tehran, rather than requiring him to stay in prison.
The UK has always said there is no link between the debt and the release of the detainees, so it would be difficult for London to explicitly make such a link.
After his return to jail, Tabhaz went on a nine-day hunger strike, but his future seems tied up with stalled talks on the resumption of the Iran nuclear deal in Vienna.
Tabhaz also has US citizenship and the Iranians appeared unwilling to release him as part of the deal that led to the release of Zaghari-Ratcliffe and Ashoori.
The foreign secretary, Liz Truss, thought that as a compromise she had reached an agreement that Tabhaz, an environmentalist arrested in January 2018 and jailed for 10 years, would be allowed out of jail on furlough. After only two days on release, he was returned to jail. There was a misunderstanding within his family, according to the Iranians.
The UK foreign affairs select committee is due to hold an inquiry into how the UK handled the detainee case, but it is not yet clear how much it will examine the issue of state hostage-taking in general or the handling of past consular cases by ministers and officials.
Zaghari-Ratcliffe was jailed for six years in Iran. Ashoori was held in prison for nearly five years in Evin. They were found guilty of spying by the Iranian revolutionary courts, charges they denied.