A doctor who had a tube put up his nose and into his stomach in protest at the treatment of hunger strikers in Guantanamo Bay said the ordeal was much worse than he expected.

David Nicholl, consultant neurologist at City Hospital, Birmingham, had the procedure performed by a nurse with 25 years experience but it took three painful attempts before the tube went in.

He was resisting the insertion to simulate the situation in Guantanamo Bay where strikers, one of which is Brighton man Omar Deghayes, have stated a determination to die because of what they allege are horrific conditions inside the military jail.

He had a thin tube inserted but prisoners at Guantanamo have claimed tubes the thickness of a finger are being used on them.

Dr Nicholl, who performed the stunt outside the US embassy in London on Tuesday, said: "It is very hard when someone is resisting to get a tube down their neck - I was surprised how much so.

"I think what they must be doing is holding them down on a flat bench then hyper-extending their neck. I can't see how else they could get the thick tubes in there.

"What I had done yesterday was horrible. What is happening to the prisoners is horrific and disgusting.

"The doctors at Guantanamo are taking orders from the military. That is the same way the Nazis operated.

"These is being done to British residents and it is shameful that the Government is letting it continue."