Britain should repay its four decade-old GBP400m debt to Iran and take serious steps to lift sanctions, Iranhas told the British foreign secretary, Liz Truss, in the first meeting between the two countries at foreign secretary level since 2018.

Truss’s meeting withHossein Amir-Abdollahian came in the week that the British-Iranian dual national Nazanin Zaghari-Ratcliffe marked her 2,000th day in detention in Iran. She is now staying with her mother in Iran, pending an appeal on her additional sentence of one year.

The two sides’ accounts of the meeting differed: Iran claimed Truss acknowledged that Britain owed the sum but said sanctions made it impossible to pay, an account not confirmed in the brief British read-out of the meeting.

The UK account focused on the need for Iran to return to the talks on the future nuclear deal in Vienna, and the need for all British dual nationals detained in Iran to be released immediately.

Talks on a prisoner swap involving detainees not just in the UK have for the moment stalled partly over one of the prisoners Iran wishes to have released from the US.

Truss spoke to Richard Ratcliffe, Zaghari-Ratcliffe’s husband, on Sunday and asked what help he needed. The Foreign Office is still reluctant to describe those being detained as state hostages, partly for legal reasons and possibly for fear they will face compensation claims.

Ratcliffe’s legal advisers Redress have also given the Foreign Office the names of 10 Iranian officials they say should be subject to human rights sanctions due to their past involvement in the detention, investigation or jailing of dual nationals.

The Foreign Office is unlikely to go down that road until they are convinced that Iran has no intention of returning to the Vienna talks.

Ratcliffe and the couple’s daughter, Gabriella, set up a giant snakes-and-ladders board in Parliament Square on Thursday to symbolise the feeling of being caught between two governments.

“It’s 2,000 days of ups and downs and twists and turns and false dawns, and snakes and ladders seemed to encapsulate that because we’re in the middle of a game between two governments. We’re just a bargaining chip in it,” Ratcliffe said.

Truss also spoke in New York about the Iran file with Sergei Lavrov, the Russian foreign minister, pressing him to urge the Iranians to return to the talks.

In a round of bilaterals the Iranian foreign minister heard a unified call from European ministers to return to the talks as soon as possible, but he has steadfastly refused to set a date, saying his newly elected government is still reviewing the file. There have even been suggestions the file will be taken from the foreign ministry as part of a move to prioritise the lifting of western sanctions in favour of building stronger links within the region.

The foreign ministry highlighted a follow-up meeting in New York and a groundbreaking meeting held in Baghdad, at which both Saudi and Iranian officials were present.

The Iranian foreign ministry spokesman, Saeed Khatibzadeh, said Iran had had “very serious talks” with Saudi Arabia on the security of the Persian Gulf.

He said: “We think that the government of the Kingdom of Saudi Arabia pays serious attention to the message of the Islamic Republic of Iran to the solution to problems in the region, within the region.”