The Government is facing calls to take immediate action against the United Arab Emirates after a British academic accused of spying with "absolutely no evidence" was jailed for life.
The Foreign Office has been accused of handling the case of Durham University PhD student Matthew Hedges "appallingly" after the 31-year-old was handed the life term during a five-minute hearing on Wednesday.
Jeremy Hunt is due to meet with his wife, Daniela Tejada, on Thursday and the Foreign Secretary has threatened the UAE with "serious diplomatic consequences" if Mr Hedges is not freed.
Ms Tejada, who was at the Abu Dhabi court, has demanded the British Government "take a stand now".
"Matthew is innocent. The Foreign Office know this and have made it clear to the UAE authorities that Matthew is not a spy for them," she told The Times.
"This whole case has been handled appallingly from the very beginning, with no-one taking Matthew's case seriously. The British government must take a stand now for Matthew, one of their citizens.
"They say that the UAE is an ally but the overwhelmingly arbitrary handling of Matt's case indicates a scarily different reality, for which Matt and I are being made to pay a devastatingly high price."
Ms Tejada's call for immediate action was echoed by Tory MP Johnny Mercer, who condemned the academic's jailing and called for the Government to be resilient.
He wrote on Twitter: "This is ridiculous. Our Defence assistance, mentoring and intelligence relationships alone with this country should preclude absurd things like this happening. From a friend and partner, simply unacceptable.
"Consequences must be immediate until he is released."
Mr Hunt said the UK "will do everything we can to get him home".
"We see absolutely no evidence for any of the charges laid against him. We're very concerned for his welfare," he told Sky News.
"The UAE is supposed to be a friend and ally of Britain's. We've given them repeated assurances about Matthew. If we can't resolve this there are going to be serious diplomatic consequences, because this is totally unacceptable."
The Middle Eastern studies specialist was arrested at Dubai Airport on May 5.
A family representative said he had since been held in solitary confinement for over five-and-a-half months, during which his "mental and physical health seriously deteriorated".
Theresa May said she was "deeply disappointed and concerned" by Mr Hedges' jailing and told MPs the UK "will continue to press this matter at the highest level with the Emiratis".
Mr Hunt was "urgently seeking a call with Foreign Minister Abdullah bin Zayed", the Prime Minister added.
At Prime Minister's Questions, Tory MP Crispin Blunt told Mrs May she should make clear to the UAE that "if he is not released, I don't see why we should be committed to their defence".
Professor Stuart Corbridge, vice-chancellor of Durham University, said he was "devastated" by the sentence.
He said: "There has been no information given on what basis Matt was handed this sentence and no reason to believe that Matt was conducting anything other than legitimate academic research."
A Foreign Office spokesman did not say what form any possible diplomatic consequences could take, but said a number of options are available.