Iran on Monday adjourned a new trial of British-Iranian woman Nazanin Zaghari-Ratcliffe, according to her husband and the UK government, which condemned what it said was her "appalling" treatment by Tehran.

Richard Ratcliffe said his wife was hauled to the court from her parents' Tehran home by Revolutionary Guards personnel, who had warned that she would be returned to jail after the hearing.

"Nazanin was allowed to respond to questions from the judge. However, before she was able to present her defence the case was adjourned," Ratcliffe said in a statement.

"No date for the next hearing has been sent, and Nazanin was returned to her parents' house. She will not sleep in prison tonight.

"But this feels like a stay of execution. It is not as though the axe has gone. It is clear that the spectacle continues."

Zaghari-Ratcliffe, who will turn 42 on December 26, had refused to pack a bag for the threatened return to jail, according to the statement.

"I am not packing away my life again," she told her family, according to her husband.

"On the way to court I kept imagining the face of (daughter) Gabriella, telling myself I would see her again. I am so relieved to be back. You have no idea. I was so stressed out.

"There is no better place than home. I am glad to be home even if just for the time being."

British Foreign Secretary Dominic Raab, who spoke to both Zaghari-Ratcliffe and her husband last week, said he was "relieved" that she remains on temporary release.

"But the Iranian authorities' treatment of her is appalling, and she should be returned home to her (UK) family without delay," he tweeted.

Nazanin Zaghari-Ratcliffe was arrested in April 2016 while visiting relatives in Iran
Nazanin Zaghari-Ratcliffe was arrested in April 2016 while visiting relatives in Iran AFP / ISABEL INFANTES

Richard Ratcliffe has campaigned for his wife's release since she was arrested at Tehran airport in April 2016 after visiting relatives with their young daughter.

Zaghari-Ratcliffe, who worked for the Thomson Reuters Foundation -- the media organisation's philanthropic arm -- denied charges of sedition.

But she was convicted and jailed for five years. She has spent more than four years in jail or under house arrest since the start of her detention.

The British embassy had requested access to Monday's hearing but was denied, according to a spokesman for Prime Minister Boris Johnson.

Richard Ratcliffe said Raab's public interventions on the case last week "sent a clear message to the Iranian authorities not to return her to prison".

But he reiterated that his wife remains a pawn in a wider dispute between Tehran and London.

Iran has long been demanding the repayment by Britain of about $520 million paid for 1,500 Chieftain tanks in the 1970s.

When the shah of Iran was ousted in 1979, Britain refused to deliver the tanks to the new Islamic republic, but kept the money.

Now, London reportedly maintains that it cannot repay the debt without violating US sanctions on Iran.

"It remains the fact that this is not our debt. It is a debt from back before Nazanin was born. Yet we are the ones being made to pay," Richard Ratcliffe said.