The wife of a UK-based Bahraini dissident was "mistreated" in the Gulf state hours after he took part in a Downing Street protest against the country's regime, it has been claimed.
Duaa Alwadaei was detained at Bahrain airport and quizzed for seven hours overnight as a reprisal after Sayed Alwadaei demonstrated when King Hamad arrived to meet Prime Minister Theresa May on Wednesday, Reprieve claimed.
Mrs Alwadaei, 25, and the couple's 19-month-old US citizen son were trying to return to London after a short visit to family and despite being a UK resident she has now been barred from leaving the tiny state, the charity said. She has also been subjected to violent threats from the police and the public, it said.
The Bahraini Embassy in London said that Mrs Alwadaei had been released to carry on her journey and denied she had been mistreated.
Reprieve director Maya Foa said: "Freedom of expression might be banned in Bahrain, but the British Government cannot allow Bahrain to punish people who demonstrate in the UK against human rights abuses such as torture and executions.
"Duaa and her baby must be allowed to leave Bahrain immediately and return to their home in London with Sayed."
Mr Alwadaei has refugee status in the UK after his role in the Arab Spring uprising in Bahrain in 2011. He was briefly held by police on Wednesday before being released, the charity said.
The Bahraini government has been accused of a string of abuses since pro-democracy protesters were violently suppressed during the Arab Spring.
The Prince of Wales was criticised earlier this month after it was announced he and the Duchess of Cornwall will visit the country as part of a Gulf tour in November.
Britain has a long-standing political, military and economic relationship with the Gulf state - which gained full independence in 1971.
But the UK's relationship with Bahrain was criticised in a report by the Commons Foreign Affairs Select Committee published in April.
A Bahraini embassy spokesman said Mr Alwadaei had a history of "being involved in and supporting terrorist acts".
He added: "Upon her departure at Bahrain's airport to her London destination, Mrs Alwadaei was briefly detained for questioning, searched and released to make her onward destination.
"At no time was she abused or mistreated by authorities.
"It bears noting that the Office of the Ombudsman is available to anyone who feels their rights have been abused and will open an investigation into matters brought to their attention.
"With regards to the specific allegations of mistreatment, at no time was Mrs Alwadaei subjected to any form of mistreatment or violence."