LONDON - Britain on Thursday denied any link between a longstanding debt of £400 million ($530 million, 450 million euros) to Iran and the fate of a British woman jailed in Tehran, after a report cited diplomats saying the money could help secure her release.
The debt dates back to an arms contract for which Britain had received an advance payment from Iran but which was halted by the 1979 Iranian Revolution.
The money is being held in a frozen bank account in Britain, but sending the funds to Iran is complicated because of European Union and US sanctions on the country.
Separately, British Foreign Secretary Boris Johnson has vowed to make every effort to secure the release of Nazanin Zaghari-Ratcliffe, who was imprisoned 19 months ago on charges of sedition.
"We don't see any link between these two issues," a spokesman for Prime Minister Theresa May told reporters.
Iranian foreign ministry spokesman Bahram Ghassemi also denied any link in comments to Iran's IRNA state news agency.
"The case of Mrs. Nazanin Zaghari and the repayment of this debt are two distinct issues and there is no connection between them," he said.
But The Daily Telegraph cited diplomats saying that repayment of the debt could speed up her release from jail.
The newspaper also quoted two senior government sources voicing concern that Zaghari-Ratcliffe was being held as "collateral" to get the money released.
The money is part of a payment of £650 million made by Iran in the 1970s to buy 1,500 Chieftain tanks from Britain and repair 250 more.
After the Shah was deposed in 1979, the deal was blocked and Britain kept the money.
Zaghari-Ratcliffe, a British-Iranian dual national who works for the Thomson Reuters Foundation -- the media organisation's philanthropic arm -- was arrested at the Tehran airport in April 2016.
She is now serving a five-year jail sentence for alleged sedition, and has been threatened with further charges and a new trial that could double her sentence.