Iran's judiciary spokesman Gholam Hossein Mohseni-Ejehi announced that Nazanin Zaghari-Ratcliffe was under investigation in a case "linked to national security matters," according to the state-run ISNA news agency.

Mohseni-Ejehi added that Iran routinely took precautionary measures to prosecute people "who attempt to infiltrate the political system."

Iran's Revolutionary Guard had reportedly detained Zaghari-Ratcliffe on April 3 at Tehran's Imam Khomeini International Airport, transferring her to a prison in Kerman province later on, according to Iranian media reports.

Her two-year-old daughter, who was travelling with Nazanin Zaghari-Ratcliffe at the time, has been staying in Iran under the care of her grandparents. She also had her British passport taken away.

Spy games

Zaghari-Ratcliffe, an employee of the Thomson Reuters Foundation, stands accused of being "involved in the soft overthrow of the Islamic Republic through [...] her membership in foreign companies and institutions," Iran's elite Revolutionary Guards said earlier in the week, according to the Mizan news agency, which is closely linked to the Iranian judiciary.

According to another statement by the Revolutionary Guards, which state that their role is to protect the Islamic system and prevent foreign interference, Zaghari-Ratcliffe was alleged to have conducted "various missions [...] leading her criminal activities under the direction of media and intelligence services of foreign governments."

Zaghari-Ratcliffe is being held in a furnished room in a prison in the southeastern city of Kerman, the statement added. However, her husband, who reportedly last spoke to her on May 30, said that she was being held in solitary confinement.

'Farcical allegations'

Zaghari-Ratcliffe's husband, Richard, dismissed the allegations against his wife as "complete nonsense."

"It's taken them 70 days to come up with this, and it's still not clear what it means anyway," he told the AFP news agency.

"If these are indeed the allegations, this is of course farcical - the idea that there is some malevolent network headed by Nazanin and her 2-year-old daughter is nonsense," Richard Ratcliffe said in another statement.

He added that is wife was "not political ... 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."

Zaghari-Ratcliffe's employer, the Thompson Reuters Foundation, confirmed that she had no professional ties to Iran

Meanwhile her employer, the Thomson Reuters Foundation, said that Zaghari-Ratcliffe had no professional ties to Iran.

"Nazanin has been working at the Thomson Reuters Foundation for the past four years as a project coordinator in charge of grant applications and training, and had no dealing with Iran in her professional capacity," foundation CEO Monique Villa said.

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

In 2012, an Iranian court found the Reuters news agency, which is part of the Thomson Reuters group, guilty of "propaganda against the regime," and "publishing false information in an effort to disturb public opinion," resulting in Iran's withdrawal of press credentials from all staff at Reuters' Tehran bureau.

Serious charges

The British Foreign Office said in a statement that it was "urgently seeking information from the Iranian authorities on the reported accusations."

British Foreign Secretary Philip Hammond has reportedly contacted his Iranian counterpart in the matter. Britain has, however, not been granted consular access to Zaghari-Ratcliffe because Iran does not recognize dual nationality. If put on trial, Nazanin Zaghari-Ratcliffe will be considered an Iranian national.

Should she be tried and convicted of espionage, Zaghari-Ratcliffe could face life imprisonment or the death penalty. Previous cases have, however, often resulted in lacking evidence and diplomatic efforts leading to acquittals.

ss/jm (AFP, AP, dpa)