Islamist extremists have infiltrated Government and key public utilities to pass sensitive information to terrorists, the security services have warned.
Counter-terrorism officials say "insiders" or their associates are almost certainly working "undetected" in sensitive posts and are actively supporting the activities of extremists.
| Mustapha Boutarfa was involved in the Paris Metro bomb attack, but was then allowed to work as a traffic warden in the UK |
In some cases, lifelong relationships between friends or relatives are being exploited to obtain crucial information from those in sensitive posts. |