LONDON: Detained British-Iranian dual national Nazanin Zaghari-Ratcliffe will face a new, unspecified charge, according to Iranian state media.

She appeared before a court in Tehran on Tuesday and was told she would face another trial on Sunday, but was not informed of the charge against her.

Zaghari-Ratcliffe was detained in 2016 on charges of “plotting to topple the Iranian government,” which she has always denied, and was sentenced to five years in prison.

Earlier this year, she was temporarily released from Evin prison, north of Tehran, to stay under house arrest with her parents as part of a furlough program to halt the spread of COVID-19 in the country’s overcrowded prison system.

Responding to the new charge, a spokeperson for the UK's foreign office said: “Iran bringing new charges against Nazanin Zaghari-Ratcliffe is indefensible and unacceptable. We have been consistently clear that she must not be returned to prison.”

Zaghari-Ratcliffe’s husband said she is being used as a “chess piece” by Tehran, and had previously expressed fears that she would face additional charges once her current sentence nears its end. 

Zaghari-Ratcliffe said authorities in Tehran had previously suggested that her release was conditional upon the UK’s repayment of a debt owed to pre-revolution Iran.

Brian Hook, the US special representative for Iran, told the BBC that such behavior by Tehran is commonplace.

“This is a practice. It’s a tool of statecraft. It’s part of Iran’s foreign policy to take people hostage who are innocent and then trade them later for some objective that they think advances their own objectives,” he said.