Accusations that a charity worker detained in Iran was trying to overthrow the country's government have been branded "crazy" by her husband.

Richard Ratcliffe said he reacted in "shock and horror" at the allegations announced on Wednesday by Iranian authorities.

His British-Iranian wife, Nazanin Zaghari-Ratcliffe has been held in an Iranian prison for more than two months without charge.

Iran's Revolutionary Guard alleged Ms Zaghari-Ratcliffe, 37, had participated in the "design and implementation of cyber and media projects to cause the soft toppling of the Islamic Republic".

Ms Zaghari-Ratcliffe, who works for the Thomson Reuters Foundation, the charitable arm of the news agency, was stopped on April 3 at Imam Khomeini airport in Tehran with her daughter Gabriella as she tried to return to the UK after a family holiday.

Mr Ratcliffe, from West Hampstead, London, said he was only alerted to the accusations by a press release on Wednesday morning.

He told the Press Association: "It is crazy and it is nonsense. I don't quite know what it means."

He said the allegations appeared to come from the provincial agency, rather than from a national authority, and called the charges "vast and vague".

Mr Ratcliffe added: "If these are indeed the allegations, this is of course farcical - the idea that there is some malevolent network headed by Nazanin and her two-year-old daughter is nonsense. It is a struggle enough for me to take Gabriella shopping."

He added: "Nazanin is not political.

"She is not an activist, but someone with a sincere moral core and great integrity. It is to Iran's shame that people like her are subjected to this treatment."

A UK Foreign Office statement said they were "urgently seeking information from the Iranian authorities on the reported accusations being made."

It added: "We have raised this case repeatedly and at the highest levels and will continue to do so at every available opportunity. We have also been supporting Mrs Zaghari-Ratcliffe's family since we were first made aware of her arrest."

Monique Villa, chief executive of the Thomson Reuters Foundation, said Ms Zaghari-Ratcliffe had "no dealing with Iran in her professional capacity".

She added "We have heard today from the Mizan news agency that Nazanin Zaghari-Ratcliffe has been accused - literally of 'being involved with foreign companies and networks in planning the overthrow of the Islamic regime in Iran through projects involving media and cyber networks'.

"The Thomson Reuters Foundation has no dealings with Iran whatsoever, does not operate and does not plan to operate in the country."

She added that the organisation remained in "close contact" with the family and the Foreign Office.

Mr Ratcliffe confirmed his wife was moved from a prison in Kerman province to the capital Tehran on Monday, meaning she should have access to a lawyer.

The couple's daughter, who turned two last week, had her British passport confiscated by the Iranian authorities and is staying with her grandparents.

Earlier this month Mr Ratcliffe left a birthday card on the doorstep of the Iranian embassy in London and sang Happy Birthday over Skype to mark Gabriella's birthday.

Under Iranian law only her father or mother can bring her home.

In a bid to reunite the family, thousands of people have sent cards to Iranian embassies across the world.

A Change.org petition has topped 764,000 signatures and Mr Ratcliffe hopes to have it sent to Iran's supreme leader Ali Khamenei once it passes one million names.

A spokesman for Amnesty International said the allegations were part of a "spurious, trumped-up case designed to exert diplomatic pressure" on Britain.

It added: "The Iranian authorities have already treated Ms Zaghari-Ratcliffe appallingly - holding her for weeks on end in solitary confinement, denying her access to a lawyer and making it nearly impossible for her to properly communicate with her desperately-worried family."

"Unless she is charged with an internationally-recognisable offence and tried in line with international fair trial standards, Ms Zaghari-Ratcliffe should be released as soon as possible and allowed to travel with her daughter back to the UK."