MI5 spies stood by and watched as the London Bridge killers loaded their van and set off to launch their attack which killed eight people last year.
A report by David Anderson QC, the Government’s former independent reviewer of terrorism legislation, confirmed ringleader Khurram Butt had been under surveillance by MI6 agents and Scotland Yard, and he was still the subject of “a live investigation” on the night of the attack.
Butt had been on MI5’s radar since mid-2015 and it was thought he was likely to be planning an attack. Up to 30 intelligence staff and undercover police were watching him around the clock.
But the surveillance operation was eventually downgraded as MI5 became more concerned with other suspects and assessed Butt as being more likely to travel to Syria to join ISIS.
And it has emerged that when he and accomplices Rachid Redouane and Youssef Zaghba were seen loading a van outside his flat in Barking, East London, before last June’s atrocity, intelligence officers did not bother calling police.
Two hours later, the vehicle was used to mow down pedestrians before the three men went on a knife spree, stabbing people at pubs and restaurants.
The disclosure about the monitoring of Butt follows claims that security services also missed opportunities to prevent the suicide bombing at Manchester Arena last May.