Iran on Tuesday told Nazanin Zaghari-Ratcliffe,a British-Iranian woman detained in Tehran, that she faces a new indictment, dampening her supporters' hopes of an early release.
She has already spent more than four years in jail or under house arrest since her arrest at Tehran airport in April 2016 after visiting relatives in Iran together with her young daughter.
Zaghari-Ratcliffe, who at the time worked for the Thomson Reuters Foundation -- the media organisation's philanthropic arm -- was convicted on sedition charges, which she denies, and sentenced to a five-year jail term.
The new indictment comes after her husband, Richard Ratcliffe, said late last month that he feared his wife could face a second trial.
"I think, behind closed doors, they keep saying there's a second court case," he told the British broadcaster ITV.
On Tuesday, Iranian state television's website Iribnews reported: "The 15th chamber of the Islamic Revolutionary Court summoned Nazanin Zaghari this morning with her lawyer... to notify them of a new indictment".
The report cited "an informed source" but gave no further details on the charges or trial date.
Tulip Siddiq, the British MP for Zaghari-Ratcliffe's constituency, tweeted that she had been in touch with the detainee, confirming that "she was taken to court this morning and told she will face another trial on Sunday".
"I know many people are concerned about her welfare and I'll keep everyone updated when we have more information," said Siddiq, a member of the #FreeNazanin campaign.
Britain's foreign ministry said bringing new charges against Zaghari-Ratcliffe was "indefensible and unacceptable".
"We have been consistently clear that she must not be returned to prison," a ministry spokesperson said.
Already in 2017, when Zaghari-Ratcliffe's family had hoped to obtain her early release, the Iranian Judicial Authority ruled out the possibility, saying there were "two cases" against her.
Zaghari-Ratcliffe has been on temporary release from Evin prison in Tehran and under house arrest since the spring due to the novel coronavirus pandemic.
Iran, the worst-hit country in the Middle East, has released tens of thousands of prisoners from its crowded jails to slow the spread of Covid-19.
- 'Collateral' -
Media in both the UK and Iran have drawn a possible link between Zaghari-Ratcliffe's detention and a British debt dating back more than 40 years, to when the shah of Iran paid the UK £400 million for 1,500 Chieftain tanks.
When the shah was ousted in 1979, Britain refused to deliver the tanks to the new Islamic Republic but kept the money.
The British government has previously admitted it owes Iran up to £300 million ($390 million), but both countries have denied any link with the Zaghari-Ratcliffe case.
"Well, of course there should be no link," the detained woman's husband told ITV. "It's completely outrageous to be holding people and using them as collateral."
British daily The Guardian reported Friday that the UK defence minister, Ben Wallace, had for the first time said he was "actively" seeking to repay a debt to Iran to secure the release of Zaghari-Ratcliffe and other Iranian-British detainees, in a letter to her lawyers.
"With regard to... the outstanding legal dispute, the government acknowledges there is a debt to be paid and continues to explore every legal avenue for the lawful discharge of that debt," he wrote.
A court hearing over the debt is set for November 4, according to The Guardian.
Zaghari-Ratcliffe is among several dual nationals and other foreigners held in Iran on security charges.
They also include Iranian-American businessman Siamak Namazi and his father Mohammad Bagher Namazi.
The Islamic republic does not recognise dual nationality and has lashed out at foreign governments for interfering in what it says are domestic cases.