Many of the Muslim women who were pulled in were carrying explosives, we can reveal.
Other radicals as young as 17 had bomb materials stashed in their homes across the country.
The operation started when a dozen women in the London and Greater Manchester areas were picked up in security sweeps but allowed to go free.
They were put under surveillance and led the spooks to more than 30 terror group leaders.
But it is feared there are at least 20 of the Black Widow bombers still at large and ready to carry out their deadly missions.
A senior security source said: “The terrorists rely on a woman in a black flowing dress not being stopped. They can’t be searched easily because of their strict rules and it’s hard to see what they are hiding under their robes.
“A lot of people would think twice about searching them for fear of offending religious rules or being accused of sexual harassment or indecency.