The wife of a British academic charged with spying in the United Arab Emirates has urged the government to state that he is innocent of the charges.

Matthew Hedges, a 31-year-old PhD student from Exeter, who is at Durham University, was arrested on 5 May at Dubai airport at the end of a study trip.

On Monday, the UAE government said he had been charged, just days after his wife, Daniela Tejada, appealed publicly for his release. She said her husband has been kept in solitary confinement since then, has been forced to sleep on the floor for months and has suffered from anxiety and depression.

On Tuesday, Tejada, 27, said: “I no longer know what to do to get Matt out of prison in the UAE. I am calling on the UK government to clarify publicly that Matt is innocent of the charges and that there have been many falsehoods said about him.

“It is the duty of the Foreign and Commonwealth Office to protect their citizens abroad. This horrifying situation has been going on for far too long.”

Tejada said her husband only met his legal representative for the first time at court last week, when she said proceedings were held in Arabic with only questions directed to Hedges translated.

He and his defence team have now been given until 24 October to prepare his case, she said.

“The prosecution has therefore had over five months to come up with a case for trial and Matt’s court-appointed lawyer has been given two weeks with no further access to Matt,” she said. “To call this a fair judicial process is, to say the least, highly inaccurate. Matt has never been allowed to speak about his case with anyone.

“He was never given the opportunity to look for a lawyer to represent him, especially as it was not known what he needed to be represented for. The charges against Matt are false and unsubstantiated, as is the purported evidence to support them.

Matt continues to be denied appropriate medical care for his mental health and remains in solitary confinement.”

The FCO said last week that the foreign secretary, Jeremy Hunt, had raised the case with his UAE counterpart. Hedges has been allowed two visits by FCO officials, during which he is said to have been barred from discussing his case, and one visit by his wife.

Hedges was arrested after an Emirati apparently reported him to the authorities for “asking sensitive questions about some sensitive departments” and “seeking to gather classified information on the UAE”.

He was researching aspects of the UAE’s foreign and domestic security strategy, including the war in Yemen.

According to a profile on the Durham University website, Hedges’ research includes Middle-Eastern politics, the changing nature of war, civil-military relations and tribalism. The university has said it is “seriously concerned” for his welfare and Amnesty International has called for his immediate release.