British-Iranian dual national Nazanin Zaghari-Ratcliffe yesterday appeared in a Tehran court to face new charges of "propaganda against the system", a week after she finished serving a five-year sentence, her lawyer said.

The hearing has dashed hopes of family and supporters for a swift release of the 42-year-old, in a case that has heightened diplomatic tensions between London and Tehran.

"The hearing took place in a very calm and good atmosphere, in the presence of my client," her lawyer Hojjat Kermani told AFP, adding that the judgement would be handed down at a later and unspecified date.

According to Kermani, she is now being prosecuted for "propaganda against the system for having participated in a rally in front of the Iranian embassy in London" in 2009.

"Given the evidence presented by the defence and the legal process, and the fact that my client has also served her previous sentence, I hope that she will be acquitted," the lawyer added.

In London, her Member of Parliament Tulip Siddiq said that "no verdict was given", but added that "it should be delivered within a week".

Zaghari-Ratcliffe was detained while on holiday in 2016 and convicted of plotting to overthrow the regime in Tehran -- accusations she strenuously denied. The mother-of-one was working at the time as a project manager for Thomson Reuters Foundation, the media organisation's philanthropic wing.