A British-Iranian mother who has been held in Iran since 2016 has been ordered to pack a bag for prison so she can appear before a judge on Monday – just days after a fresh trial was postponed.

Nazanin Zaghari-Ratcliffe, a British-Iranian dual national, was convicted of plotting to overthrow the government in 2016 – an accusation she completely denies.

Her husband Richard Ratcliffe, who lives in north London, said the new trial would hear charges of spreading anti-government propaganda. It had been due to take place on November 3 has now been postponed until after the end of her current sentence.

Having been moved to house arrest in March, when thousands of prisoners were granted clemency and freed from Iranian jails amid the Covid-19 outbreak, Zaghari-Ratcliffe was returned to court last week only months away from her expected release date, and told she would face a second trial.

Meanwhile Labour’s Tulip Siddiq – who is Zaghari-Ratcliffe’s MP – said: “She is being treated with contempt.”

Siddiq urged Prime Minister Boris Johnson to step up the efforts to bring her back to the UK.

Richard Ratcliffe has called on foreign secretary Dominic Raab to assert Britain’s right to attend the trial and visit his wife.

In a statement, Ratcliffe said Raab had reassured him that “the UK’s diplomatic push is ongoing and despite recent events, the government still does not judge it time to change strategy.

“We disagreed on this. Seclusion of the victim, with bouts of conspicuous cruelty in the face of decisions to wait, are key pillars of hostage taking. Both must be challenged robustly if British citizens are going to be protected from hostage diplomacy by Iran or others.

“As Nazanin’s husband, I do think that if she’s not home for Christmas, there’s every chance this could run for years. So I really hope there’s something we’re not being told, as on the face of it the government’s response seems disastrous, just extraordinary that they won’t change course.”

Zahari-Ratcliffe will appear before Judge Salavati on Monday where she will learn more about her latest summons.