Nazanin Zaghari-Ratcliffe has been sentenced to another year in prison after being found guilty of propaganda activities against the regime in Iran.

The British-Iranian charity worker was also given a one-year ban from leaving the country.

Her lawyer said she had been accused of taking part in a demonstration in London 12 years ago and giving an interview to the BBC Persian service.

The Prime Minister said the UK would "redouble" efforts to free her, with the UK Government now facing mounting calls to impose sanctions. 

Her husband Richard Ratcliffe told the BBC the court's decision was "clearly a negotiating tactic" by the Iranian authorities - who are currently in discussions over the country's nuclear activities.

She has not been taken to prison yet and plans to appeal.

Asked about her sentenced during a visit to North Wales today, Boris Johnson said that the Government will be “working very hard” to secure Ms Zaghari-Ratcliffe’s release.

The Prime Minister said: “Obviously we will have to study the detail of what the Iranian authorities are saying.

“I don’t think it is right at all that Nazanin should be sentenced to any more time in jail.

“I think it is wrong that she is there in the first place and we will be working very hard to secure her release from Iran, her ability to return to her family here in the UK, just as we work for all our dual national cases in Iran.

“The Government will not stop, we will redouble our efforts, and we are working with our American friends on this issue as well.”

Foreign Secretary Dominic Raab said the sentence was "inhumane".

He said: "This is a totally inhumane and wholly unjustified decision.

“We continue to call on Iran to release Nazanin immediately so she can return to her family in the UK. We continue to do all we can to support her.”

Layla Moran MP, Liberal Democrat Spokesperson for Foreign Affairs, called for targeted sanctions to be introduced against Iran.

She said: "This is a cruel and heartless decision by the Iranian regime.

"Nazanin should be coming home to her family, instead she’s being used as a political bargaining chip yet again.

"Enough is enough. The Foreign Secretary must now begin the process of introducing targeted Magnitsky sanctions against officials responsible. With Nazanin’s health deteriorating and her family in distress, strong words must be backed by real action.

"Nazanin has been put through hell for five years and today's verdict will prolong her suffering even more. The Government must do everything in its power to bring her home to her family immediately.” 

Labour MP Lisa Nandy, shadow foreign secretary criticised the Government’s handling of the case.

The Labour MP tweeted: “This is devastating news. Nazanin’s freedom is being used as a political bargaining chip and the Government has serious questions to answer over their failed strategy to bring her home."