Prime Minister David Cameron has expressed his concern over allegations three British men were tortured by police in Dubai after they were arrested on drug charges.
Grant Cameron and Suneet Jeerh, both 25, and Karl Williams, 26, are on trial accused of having a quantity of a synthetic cannabis known as "spice" in their car while on holiday in July last year.
The men, all from London, claim they signed documents in Arabic - a language none of them understands - following their arrests after they were threatened with guns to their heads, said the human rights charity Reprieve.
Mr Williams also reported having electric shocks administered to his testicles during the ordeal, the charity added. The men have denied charges of "consumption and possession with intent to distribute" and are expected to learn their fate tomorrow when a Dubai judge delivers his verdicts in the trial.
In a letter to Reprieve, the Prime Minister has said he will use a state visit by the United Arab Emirates (UAE) president in the coming week to raise his concerns about the case.
Mr Cameron wrote: "The UK Government takes all allegations of mistreatment very seriously. We continue to press for evidence for a full, impartial and independent investigation into the allegations. The absence of an independent medical examination remains a concern."
He continued: "During the state visit of His Highness Sheikh Khalifa bin Zayed Al Nahyan there will be opportunities to raise a wide range of issues including concerns about this and other consular cases. We continue to request these cases are fully and independently investigated. I appreciate this must be an extremely difficult time for Mr Cameron, Mr Williams and Mr Jeerh and their families."
The men appeared at their first trial hearing in February after spending seven months in custody.
In a draft witness statement provided to Reprieve lawyer Marc Calcutt, Mr Williams described having a towel put on his face by police and having electric shocks on his testicles. The torture, which the police deny, allegedly took place in the desert, where the men were initially taken after their arrest, and subsequently in hotel rooms.
Mr Cameron's mother Tracy said her son's ordeal had been "absolutely awful" but he remained in "good spirits" ahead of the court hearing.