A British academic sentenced to life imprisonment by the United Arab Emirates on an espionage charge has arrived in London after being pardoned by the nation's president.

Matthew Hedges was freed yesterday as part of a national day of clemency by the UAE, but officials persisted in calling him an MI6 spy, a claim denied by family and colleagues.

The Durham University PhD student, originally from Exeter, was sentenced last Wednesday after being arrested at Dubai Airport as he tried to leave on 5 May.

In his first statement since his release, Mr Hedges said: "I don't know where to begin with thanking people for securing my release.

"I have not seen or read much of what has been written over the past few days but Dani tells me the support has been incredible. Thank you so much to the British Embassy and the FCO (Foreign Office) for their efforts in ensuring I arrived safely back home.

"I could not have done this without Daniela, I hear her face is everywhere!"

"She is so brave and strong, seeing her and my family after this ordeal is the best thing that could have happened. I thank you all once again, this is very surreal."

Mr Hedges' wife, Daniela Tejada, mounted a campaign to free the 31-year-old and British Foreign Secretary Jeremy Hunt personally discussed the case with UAE leaders.

At a news conference yesterday in Abu Dhabi, officials showed a video of Mr Hedges describing himself as a captain in MI6 during what appeared to be a court hearing.

However, MI6 - the foreign intelligence service - is not known to use military ranks.

An official told reporters in Abu Dhabi that Mr Hedges was "100% a full-time secret service operative" who was in the country "to steal the UAE's sensitive security national secrets for his paymasters".

He said the Briton's pardon came in response to a letter from his family appealing for clemency and due to the historical close ties between the UK and UAE.

Ms Tejada said: "I am so happy to have my Matt home!

"Thank you once again for the overwhelming support we have received, especially from the embassy in the UAE and the Foreign Office in ensuring that Matt was safely returned home. We are overjoyed and exhausted!

"Thank you once again as well to the international community and the international media who were very supportive from the beginning.

"I hope you can all understand that Matt and I, as well as his family, really need some time to process everything that we have been through. No one should ever have to go through what he did and it will take him time to heal and recover. He is very overwhelmed.

"To say we are happy is an understatement."