Four British terrorist suspects passed by the US authorities to the British after spending three years in the Guantanamo prison were released from police custody last night.
Pentagon officials said they continued to believe Mr Moazzam Begg, Mr Feroz Abbasi, Mr Martin Mubanga and Mr Richard Belmar posed a "significant threat".
But Mr Azmat Begg, father of Moazzam, said nothing had been proved against his son, despite hundreds of interviews in Guantanamo.
"I have heard from my son that they have taken more than 300 interviews and interrogators came down to his cell," he said.
"Everything has been done and nothing has been proved. No evidence is there of anything but if the United States want to say things it's up to the United States."
A Pentagon spokesman said: "British authorities have assured us that they will take the necessary steps to address the threat posed by these individuals. I believe the UK did not have the information they needed to charge these individuals."
The four men had been held under the Terrorism Act 2000 and questioned by anti-terrorist officers after being flown back to west London on Tuesday night.
All four men had been kept in legal limbo as suspected terrorists at the US naval base in Guantanamo for three years and were released after extensive discussions between the US and the UK Government.
Lawyers said the men had been deeply traumatised by their experiences and human rights groups welcomed their release.
PA