French-Iranian academic Fariba Adelkhah was jailed anew for breaking house arrest restrictions, an official from the Islamic republic's judiciary authority said on Sunday.

Her Paris-based support group had on Wednesday announced "with great shock and indignation" her re-incarceration, which comes during sensitive talks in Vienna aimed at reviving a 2015 nuclear deal which offered Tehran sanctions relief in exchange for curbs on its nuclear programme.

"Ms Adelkhah... has unfortunately knowingly violated the limits of house arrest dozens of times," Kazem Gharibabadi, deputy head of the judiciary, was quoted as saying by Mizan Online, the authority's news agency.

"She has insisted on doing so despite repeated warnings from judicial authorities. So now, like any other prisoner who has violated the same rules... she has been returned to prison," he added.

Adelkhah, 62, an expert on Iran and Shiite Islam at France's prestigious Sciences Po university, was arrested on June 5, 2019, at Tehran airport.

She was sentenced in May 2020 to five years' imprisonment for conspiring against national security, accusations her supporters have always denounced as absurd. In October of that year, she was placed under house arrest with an electronic bracelet.

Adelkhah's support group on Sunday rejected the judiciary's accusations and said she had followed the rules.

Her house arrest, sentencing and initial arrest "have never had the slightest foundation", said Beatrice Hibou, head of research at the National Centre for Scientific Research (CNRS) in Paris, calling the measures "unfair and illegitimate acts".

The judiciary's assertions are "null and void and will not silence the indignation that rose around the world at the announcement of her re-incarceration," she said, adding: "Fariba Adelkhah is innocent."

- 'Entirely arbitrary' -

Adelkhah is one of at least a dozen Western nationals believed to be held in Iran who rights groups abroad say are being detained for political reasons to extract concessions from the West.

The French foreign ministry said her re-imprisonment "can only have negative consequences on the relationship between France and Iran and reduce confidence between our two countries."

French President Emmanuel Macron on Thursday called the decision "entirely arbitrary". He added that "the whole of France" was "mobilised for her release".

Gharibabadi insisted that Adelkhah is "a citizen of the Islamic republic of Iran", which "firmly condemns the intervention of other countries in (its) judicial process."

Iran does not recognise dual nationality so denies French consular staff access to Adelkhah.

"It is very unfortunate that the French authorities... by issuing hasty statements, make baseless and unfounded remarks that are definitely unacceptable," Gharibabadi said.

Talks between Tehran and global powers on the 2015 nuclear deal entered the New Year with positive signals emerging, including the European Union saying on Friday that a deal remained possible.

Iran's foreign ministry spokesman last week cited "good progress" but French Foreign Minister Jean-Yves Le Drian on Friday reiterated his view that the talks were progressing "much too slowly to be able to reach a result".

Then-president Donald Trump had pulled the US out of the agreement in 2018 and reimposed biting sanctions, prompting Tehran to begin rolling back on its commitments.