MICHAEL Gove has been accused of compounding the threat to a British citizen jailed in Iran for spying by saying he didn’t know why she was in the country in the first place.

Despite Nazanin Zaghari-Ratcliffe’s family and the UK government insisting she was on holiday, the Environment Secretary appeared to cast doubt on the explanation.

He would “take her husband’s assurance” that Ms Zaghari-Ratcliffe, 38, was on holiday when she was detained 18 months ago, he said.

Labour accused him to trying to protect his fellow Brexiter, Foreign Secretary Boris Johnson, who is under fire for claiming Ms Zaghari-Ratcliffe was training journalists.

Mr Johnson’s gaffe before a Commons committee last week led to the Iranian judicial system adding extra charges, leading to fears her current five-year sentence could be doubled.

The Foreign Secretary’s “inadvertent confession” was seized on as evidence of her guilt.

UK Labour leader Jeremy Corbyn and Labour’s London mayor Sadiq Khan both said on Sunday that Mr Johnson should resign or be sacked for his incompetence.

But Mr Gove defended him as “doing a great job” and said it was "plain wrong" to find fault with democrats when Iran was a regime with “blood on its hands”.

Asked what Ms Zaghari-Ratcliffe was doing in Iran, he told BBC One's Andrew Marr Show: "I don't know. One of the things I want to stress is there is no reason why Nazanin Zaghari-Ratcliffe should be in prison in Iran so far as any of us know."

Told that Richard Ratcliffe said his wife was in Iran on holiday, Mr Gove added: "In that case, I take exactly her husband's assurance in that regard."

Asked if she had been training journalists, he said: "Her husband said she was there on holiday and her husband is the person who should know."

Jon Trickett, the shadow Cabinet Office minister, said: "Boris Johnson’s cavalier approach to international diplomacy is compounded by Michael Gove claiming he has no idea what Nazanin Zaghari-Ratcliffe was doing in Iran.

“It has always been clear: she was on holiday visiting her family.

“It appears Gove is more interested in protecting Johnson’s job than the liberty of a British citizen in jail in Iran. Theresa May must ensure Nazanin Zaghari-Ratcliffe does not pay the price for her ministers’ bungling.”

Following Gove’s comments, the Free Nazanin campaign tweeted: “The UK government has no doubt Nazanin was on holiday in Iran.”

Later on Sunday, Mr Johnson had a “constructive” phone conversation with Mr Ratcliffe, and the pair agreed to meet this week or next.

Asked if Mr Johnson was unsackable, Brexit Secretary David Davis told Sky News' Sunday with Niall Paterson: "Why would you want to sack him? He's a good Foreign Secretary."