A British-Iranian mother jailed in Tehran has lost a final appeal over her conviction for allegedly plotting to topple the government.

Nazanin Zaghari-Ratcliffe (38) was arrested at Tehran Airport on April 3rd last year as she attempted to return to the UK following a holiday with her two-year-old daughter.

The charity worker was sentenced to five years in prison on "secret charges", with Iranian news agencies reporting she was convicted of plotting the "soft toppling" of Iran's government.

Mrs Zaghari-Ratcliffe maintains her innocence but has seen a final appeal over her conviction turned down by Iran's Supreme Court.

The 38-year-old's husband said the decision was "not a surprise".

Richard Ratcliffe said: "We have had two secret trials and now a closed panel review.

"But it is still nonsense that even at this stage Nazanin still does not have firm details of the charges against her."

Richard Ratcliffe, husband of British-Iranian mother and charity worker Nazanin Zaghari-Ratcliffe, takes part in a vigil outside the embassy of Iran in London | Image: Kirsty O'Connor/PA Wire/PA Images

He added: "As her husband, I can say Nazanin is innocent until I am blue in the face.

"I have spent a year doing it. But it makes a clear difference that the government hasn't.

"It indulges the whispers."

Health concerns

Mrs Zaghari-Ratcliffe's daughter, Gabriella, remains in Iran with family after her passport was seized.

Iran does not recognise dual nationalities, and those detained cannot receive consular assistance.

Mrs Zaghari-Ratcliffe's family say Iran's paramilitary Revolution Guard tried to get her to confess on camera that she trained and recruited spies.

Amnesty International say she is being held in Tehran's Evin Prison and is suffering with numerous health conditions - including severe arm, neck and back pain.

The charity says there have also been serious concerns over her mental state.

Earlier this month, campaigners gathered to mark a year since she was detained in Tehran.

The UK Foreign and Commonwealth Office has said it is "deeply concerned" over her conviction.

It added: "We are continuing to press the Iranians for consular access and for due process to be followed, and are ready to help get her daughter back safely to the UK if requested."