A British man held in Guantanamo Bay for almost three years has spoken out against the possible extradition to the US of a British terror suspect.
Mr Mubanga was outside Mr Ahmad's hearing on Wednesday
In his first television interview since returning to Britain last month, Martin Mubanga said Babar Ahmad would not be treated fairly if extradited.
Mr Ahmad, a 31-year-old computer expert from London, is accused of running websites in support of terrorism.
His lawyer told his extradition hearing Mr Ahmad faced a "denial of justice".
In claims dating back to 1997, the US government accuses Mr Ahmad of "conspiring to support terrorism", saying he "sought, invited and solicited contributions" via websites and emails.
The US also claims Mr Ahmad had plans for one of its Navy battle groups in the Gulf, including comments on how ships were vulnerable to attack.
Mr Mubanga, 32, was among a group of protesters outside the court, calling for the extradition request to be denied.
"I have come here to express my support for Babar and other brothers who are being detained without trial," he told the BBC.
"I do not believe that the Americans will give him a fair trial, as they also failed to give me a fair trial.
"The Americans are not interested in a fair trial or in the truth, they are only interested in a result."
Mr Mubanga, who has dual British and Zambian nationality, was one of four Britons who were released from the US camp in January.
He claimed he was mistreated while in US custody and is considering suing the British government, which he believed helped send him to Guantanamo Bay, his lawyer said last month.
He told the BBC he is now planning to start campaigning on behalf of those who may be facing similar situations.
Babar Ahmad, pictured in green, is fighting extradition to the US
"I am going to do what I feel I have to do to help myself and my brothers and to try and correct some of the injustices that I see in the world.
"I will be in touch with Babar's father and other families who are going through emotional stress and other people who feel the way that I feel and we will put something together to try and bring about true justice."
If Mr Ahmad loses the hearing at Bow St Magistrates' Court in London, expected to last two or three days, it will be up to the home secretary to decide if he should be sent to the US.
It is believed Mr Ahmad's legal team, led by Edward Fitzgerald QC, would appeal against such a ruling if it was made.
"There is a real risk that the defendant will suffer a flagrant denial of justice if returned," he told the hearing on Wednesday.