A group of senior doctors has called for a London man held in Guantanamo Bay to be released, warning of his "fragile medical condition".
Medics said that Shaker Aamer was suffering from conditions including post-traumatic stress disorder and asthma and his continued detention was having an "appalling effect" on his health and that of his family.
Prime Minister David Cameron is expected to again raise Mr Aamer's case with President Barack Obama during his visit to Washington this week.
Mr Aamer, who is originally from Saudi Arabia but moved to Battersea, London, and has a wife and four children there, has been incarcerated at the controversial US detention centre since 2002.
In a letter to a national newspaper, the health experts, including consultants and professors, said Mr Aamer had "pressing medical concerns".
The signatories include three members of the Foreign Office pro bono medical panel, which can assist with advice for Britons held overseas but which the doctors said had so far not been allowed to help Mr Aamer.
The letter was organised by David Nicholl, a consultant neurologist, human rights activist and member of the council of the Royal College of Physicians, and is signed by physicians, including professors of neurology and public health, consultants and GPs.
Cori Crider of the campaign group Reprieve has called on the Foreign Secretary William Hague to do more to ensure the release of Shaker Aamer, the Londoner who is still being held in Guantanamo Bay.
The director of the legal charity Reprieve has urged the UK Government to do more to help Shaker Aamer.
A South Londoner who is being held in the US detention camp in Guantanamo Bay has gone on hunger strike. Shaker Aamer has been held at the base for eleven years but has not been tried or charged.
Mr Aamer has said he has lost over 30 pounds since he joined the strike. Lawyers for the inmates say around three-quarters of them have gone on hunger strike at the camp.
Comedian Frankie Boyle has today announced a defamation suit against MI5 and MI6 on behalf of Shaker Aamer, the last remaining British resident held in Guantanamo Bay.
Boyle joined legal action charity Reprieve in London this morning to confirm the launch of the captive's legal action.
Mr Aamer, who was rendered to Guantanamo in 2002, alleges that the intelligence agencies have told lies about him, claiming he holds links with al Qaeda, which prevent his release despite politicians in both the UK and US requesting he be freed.
Ahead of the announcement Boyle tweeted: "Shaker Aamer, with a British family and a kid he's never seen, (is) just trying to get home."
Andrew Pringle, president of KBR (UK), said:
Reacting to the news that a company behind the U.S. detention centre Guantanamo Bay is bidding for a police contract in the UK, Shadow policing minister David Hanson said:
A spokesman for KBR stressed that there is a new management team in place since the company built the controversial detention centre:
A major US engineering and construction company which helped build the Guantanamo Bay detention centre in Cuba, is bidding for a role in the largest police privatisation scheme in the UK.
KBR, a former subsidiary of the controversial Halliburton group, is seeking a role in the £1.5 billion contract from West Midlands and Surrey Police.