Nazanin Zaghari-Ratcliffe, a British-Iranian dual citizen, is serving a five-year prison sentence after being convicted in 2016 of spying charges, which she denies.
Richard Ratcliffe delivered the letters on Wednesday morning in the hope that they will reach Abbas Araghchi, the deputy foreign minister of Iran, who is currently visiting the UK.
Mr Ratcliffe said outside the embassy in Kensington, west London: “We’re delivering the letters today because of the opportunity of the deputy foreign minister being here.
“He’s here to improve relations between Iran and the UK and we want Nazanin to be right at the front of that.”
Ms Zaghari-Ratcliffe, a charity worker for the Thomson Reuters Foundation, maintains that she was in Iran to introduce her daughter Gabriella to her parents.
Foreign Secretary Boris Johnson later told a parliamentary committee that Ms Zaghari-Ratcliffe had been training journalists in Iran, worsening her situation. He later apologised for this.
Mr Ratcliffe was joined at the embassy by campaigners from Amnesty International.
Kate Allen, director of Amnesty International UK, said: “She is a British citizen, she should be here with her daughter.
“We will not rest until that is achieved.”
Source : EXPRESS