Babar Ahmad, accused of running a US-hosted website which encouraged terrorism, said he has never been formally questioned about the allegations against him or been presented with any evidence.
Mr Ahmad admitted he had previously fought “battles” in Bosnia but said he believed “terrorism to be wrong”.
He told the BBC: “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.
“It is fair to say I’m fighting for my life and I’m running out of time.”
Mr Ahmad said that if he had been charged and tried in 2003, he would likely have been released from prison by now, even if he had been found guilty.
He accused the British police of “outsourcing” the case to the Americans.
He said: “Had the police and CPS put me on trial in 2003 – which they could have done – I would have left prison years ago regardless of the outcome.
“I absolutely reject any allegation that I have supported terrorism and in any way and in any place – whether in Chechnya, or Afghanistan.
“I believe terrorism to be wrong and I believe targeting and killing innocent people to be wrong.”