Terror suspects continue to avoid prosecution because British security services fear their secret sources could be exposed by public trials, a Parliamentary committee heard.
The claims that it is not possible to protect the public by prosecuting suspected terrorists were described by MPs as “extraordinary”.
David Anderson, the independent reviewer of terrorism legislation, told the Parliamentary committee on human rights that some six suspects were currently subject to terrorism prevention and investigation measures (Tpims) because independent judges believed them to be involved in terror plots.
But he said they could not be prosecuted due to MI5's “reluctance” to use human sources in an open trial, claiming there was a fear of endangering sources who were not employed by the home security service but provide it with secret intelligence.
“The reasons why these people weren't prosecuted - or were prosecuted without reference to all the intelligence - was about a reluctance to use human source reporting in an open criminal trial for fear of compromising or even endangering a source,” said Mr Anderson.
Mr Anderson questioned whether security agencies were “too cautious” in their approach, adding that there was “no doubt” the best solution was to prosecute.
Tpims, unlike the controversial control orders they replaced, have a maximum time limit of two years, meaning the six suspects will be free by early next year.