Boris Johnson is reportedly travelling to Iran this weekend to try and secure the release of jailed British mother Nazanin Zaghari-Ratcliffe.
Mrs Zaghari-Ratcliffe is serving a five-year sentence over allegations, which she denies, of plotting to overthrow the Tehran government, having been arrested in 2016 during a holiday visit to show her baby daughter Gabriella to her parents.
She is facing a further court appearance this month, following threats to increase her sentence by five years as a result of a gaffe by Mr Johnson.
The Foreign Secretary wrongly told a parliamentary committee that she had been in Iran to train journalists. He later acknowledged that this was not the case.
The Foreign Office refused to confirm the trip.