Iranian state TV has claimed Britain will pay a £400 million debt to Tehran in a move that could pave the way for the release of Nazanin Zaghari-Ratcliffe.
But there was no immediate acknowledgement from the UK Government on Sunday that a deal had been struck over the long-running dispute cited as a reason for her detention.
Quoting an anonymous official, a state broadcaster said deals had been reached with both Britain and the US in order to release prisoners with Western links held in Iran.
It was said the UK had agreed to pay the £400 million debt over the non-delivery of tanks dating back to the 1970s.
The US was said to have agreed a prisoner swap in exchange for the release of seven billion dollars (£5 billion) of frozen Iranian funds, but Washington did also not immediately acknowledge any deal.