The husband of Nazanin Zaghari-Ratcliffe, the British-Iranian woman who has been detained in Iran for more than five years, has gone on a hunger strike again after a court decided she has to serve an additional year in prison.

Richard Ratcliffe started his fast on October 24 outside the British government's Foreign Office in central London.

He plans to maintain a "constant vigil" by sleeping in a tent outside the building's main entrance in an effort to pressure Prime Minister Boris Johnson to secure the release of his wife and other detained dual British-Iranian nationals, Amnesty International said.

Zaghari-Ratcliffe was first jailed in 2016 after being accused of plotting against the regime -- charges that she, her supporters, and rights groups deny.

She was sentenced to another year's confinement in April on charges of 'spreading propaganda against the system" while participating in a protest in front of the Iranian Embassy in London in 2009.

She spent the final year of her initial sentence on parole at her parents' home in Tehran in 2020 as Iran temporarily released thousands of inmates in response to the coronavirus pandemic.

The initial court ruling against Zaghari-Ratcliffe was five years plus a one-year ban on traveling abroad. The extra year added to her sentence means Zaghari-Ratcliffe cannot leave Iran to join her husband and 7-year-old daughter in London for nearly two more years.

Ratcliffe went on a 15-day hunger strike two years ago outside the Iranian Embassy, a move he credits with getting their daughter released.

'We are now giving the U.K. government the same treatment. In truth, I never expected to have to do a hunger strike twice. It is not a normal act,' Ratcliffe said on his Change.org petition.

He said Iran remains the "primary abuser" in Nazanin's case, but that the 'U.K. is also letting us down.'

'It is increasingly clear that Nazanin's case could have been solved many months ago - but for other diplomatic agendas,' he said. 'The PM needs to take responsibility for that."

Employed by the Thomson Reuters Foundation, the charitable arm of the Reuters news agency, Zaghari-Ratcliffe was taken into custody at Tehran Imam Khomeini International Airport in April 2016 when she tried to return to Britain after visiting family in Iran.

Rights groups accuse Iran of holding dual-nationals as bargaining chips for money or influence in negotiations with the West. Tehran denies the accusation.

With reporting by AP

Copyright (c) 2018. RFE/RL, Inc. Republished with the permission of Radio Free Europe/Radio Liberty, Washington DC 20036