Britain will soon repay a debt of over 400 million pounds ($527 million) to Iran, the Iranian ambassador said on Friday, but the payment was not linked to the case of a British-Iranian charity worker jailed in Iran.

“An outstanding debt owed by the U.K. to Tehran will be transferred to the Central Bank of Iran in the coming days. The payment ... has nothing to do with Nazanin Zaghari-Ratcliffe’s case,” Hamid Baeedinejad wrote on his Telegram channel.

Zaghari-Retcliff was detained in April 2016 in Tehran by Iran’s elite Revolutionary Guards as she tried to leave Iran after a visit with her two-year-old daughter.

She was sentenced to five years in prison after an Iranian court convicted her of plotting to overthrow the clerical establishment. She denies the charges. Iran doesn’t recognize dual citizenship for its nationals.

Britain’s Foreign Office was not immediately available to comment on the Iranian ambassador’s comments.

On Thursday, British Prime Minister Theresa May’s spokesman denied there was any link between the debt and the charity worker’s case. Tehran also dismissed the Telegraph report.

The Telegraph newspaper reported on Thursday that Britain was working on a plan to pay Iran the debt, as part of efforts to secure the release of Zaghari-Ratcliffe, a project manager with the Thomson Reuters Foundation.

The Thomson Reuters Foundation is a charity organization that is independent of Thomson Reuters. It operates independently of Reuters News.

Britain owes the money after Iran’s Shah paid up front for 1,750 Chieftain tanks and other vehicles, almost none of which were eventually delivered after the Islamic Revolution of 1979 toppled the U.S.-backed leader.

In 2009, the International Chamber of Commerce ordered Britain to repay Iran £450 million ($592 million) for the tanks that were never delivered, but UN and EU sanctions levied against Iran prevented the repayment.

Under a deal between Iran and six major powers in 2015, most sanctions on Iran were lifted last year, in exchange for Tehran curbing its nuclear program.

Iran’s Foreign Ministry spokesman said that a range of issues would be discussed with Britain during a visit to Tehran this month by Foreign Secretary Boris Johnson, Iranian media reported on Thursday.