UK Prime Minister Boris Johnson has been accused of “dismal failure” in standing up to Tehran and securing the release of a dual national detained in Iran since 2016.

Tehran has sentenced Nazanin Zaghari-Ratcliffe to another year in prison and a year-long travel ban on new charges of “spreading propaganda” against the regime. Her re-imprisonment has been condemned by the British government.

Labour MP Tulip Siddiq, the representative in the family’s constituency, said Zaghari-Ratcliffe is a “victim of torture” at the hands of the Iranian state.

“At the heart of this case is the prime minister’s dismal failure to release my constituent,” Siddiq added. “The prime minister did not even arrange for UK officials to attend Nazanin’s recent court hearing, which might have ensured she got a free and fair trial.”

Middle East and North Africa Minister James Cleverly said Siddiq’s anger is “misdirected” as Iran is to blame for holding innocent people in detention.

“Our priority has always been her full release and for her to return to the UK. The UK does not and will never accept our dual nationals being used as diplomatic leverage, and we recognize her treatment has been completely unacceptable,” Cleverly said.

“It is totally inhumane and unjustified, and we call upon Iran to allow Zaghari-Ratcliffe to return home to the UK and release from detention all British dual nationals that are being held,” he added.

“This government remains committed to doing all that we can to secure Zaghari-Ratcliffe’s return home to the UK so that she can be reunited with her daughter Gabriella and her husband Richard.”

Husband Richard Ratcliffe said their daughter had not been told that her mother is being sent back to prison.

He added that he does not want Gabriella, 6, to “live too closely to the ups and downs” of the legal case as it “has been in the shadow for all the time she’s been growing up.”

He said: “We haven’t sat down and explained to her that we think mummy could be in prison for another year. We felt it was better to wait until that actually happens before stressing that.”

Cleverly rebuked Tehran’s behavior as “indefensible,” saying it is “unacceptable that Iran has chosen to continue this wholly arbitrary court case against Zaghari-Ratcliffe.”

He added: “The Iranian government has deliberately put her through a cruel and inhumane ordeal. We continue to call on Iran in the strongest possible terms to end her suffering and allow her to return home.”