Babar Ahmad, who is accused of running a US-hosted website which encouraged terrorism, said he has never been formally questioned about the allegations against him.
Ahmad, speaking on the BBC Radio 4 World at One programme following a High Court challenge by the broadcaster to secure the interview, admitted he had previously fought “battles” in Bosnia but said he believed “terrorism to be wrong”.
He told the programme: “I am facing extradition to the United States and spending the rest of my life in solitary confinement.
“I have never been questioned about allegations against me and I have never been shown any evidence against me.”
Ahmad said that if he had been charged and tried in 2003, he would likely have been released from a British prison by now, even if he had been found guilty.
The BBC carried out its Newsnight interview at HMP Long Lartin, Evesham, Worcestshire, following a year-long battle by the BBC against the Ministry of Justice for the right to broadcast and film an interview with Babar Ahmad.