“Her ordeal was exacerbated when Iran made clear they would not allow her to leave Tehran airport unless Nazanin signed a document.”

The minister said a UK official was present “to help facilitate” the departure of Ms Zaghari-Ratcliffe and Anoosheh Ashoori – another British-Iranian national freed at the same time, having been held on spying charges since 2017.

Ms Milling said the official “passed on the message from the IRGC (Islamic Revolutionary Guard Corps) that she needed to sign a confession”.

“Given the situation Iran put Nazanin in at the airport, she took the decision to sign the document,” the minister added. No UK official forced Nazanin to do so.

Ms Siddiq said she did not accept “what the minister is saying that no one forced her”.

She said that in the days leading up to her release Iranian authorities had tried to make Ms Zaghari-Ratcliffe write out and sign a document listing the false allegations she faced “admitting guilt for them, requesting clemency and promising not to sue or critics the Iranian government”.

At Tehran airport on 16 March, on the day she was eventually allowed to fly back to the UK, she was asked again to do this by Iran, but instead she tore up the piece of paper,” the MP said.

It was only when a UK official told her that she had to sign it if she was going to board the plane that was waiting to take her home that she finally caved and gave Iran what they wanted.

“Nazanin returned home but the toll this took on my constituent after six years of detention is unimaginable and unacceptable.”

Shortly after her release, Ms Zaghari-Ratcliffe criticised the UK government for the delay in securing her freedom, saying “what happened now should have happened six years ago”.

It came after the UK settled a £400m debt with Iran dating back to 1979.