A report by British think-tank the Quilliam Foundation says confining prisoners who are considered Islamic extremists with other non-extremist inmates can create more terrorists.
The foundation, set up to tackle extremism in the UK, has called on the British government to stop housing al-Qaeda leaders with other prisoners as they say it leads to radicalisation and to the smuggling of propaganda onto the internet.
James Brandon is a senior researcher at the Quilliam Foundation and author of the report.
In a statement, Britain's Ministry of Justice, which runs the prison service, said they have a expert unit which tackles extremism and radicalisation in jails and monitors inmates with links to terrorism.
But they also say they are willing to listen to any practical ideas on how to do more.
First broadcast 16 November 2009