An 18-year-old girl has been found guilty of plotting a murderous knife attack at London’s British Museum with the UK’s first all-woman terror cell which was in contact with Islamic State in the Middle East.

Safaa Boular, now the UK youngest convicted female terrorist, had been trying travel to Syria and marry an Islamic State fighter, but when police foiled her attempt she turned her attention to killing people in the UK.

She built a network of up to 400 Islamic State-linked contacts but claimed in court she had been groomed by one man and was the victim.

Her older sister Rizlaine, 22, and her mother Mina Dich, 44, pleaded guilty at an earlier hearing to continuing plotting and planning another attack, after Safaa was arrested in April 2017, London’s Metropolitan Police said.

The mother, of French-Moroccan origin, remarried an Iraqi man in 2012, who according to friends had two wives.

British intelligence had posed as a terrorist to trick a notorious British Islamic State member in Syria into revealing a plot to use the women to strike targets including Buckingham Palace and Parliament.

When a drone killed the jihadist, the officers then pretended to be his commander and a jihadi bride in Syria to talk to Safaa, who was then just 17 years old.

The trio, including a mother and daughter in full face veils, appeared in court via video link. https://t.co/mZZlmzADzl — Breitbart London (@BreitbartLondon) August 12, 2017

Police also bugged their home and overheard Rizlaine practising her attack with a knife. When she was arrested on April 27th, 2012, she was shot four times after charging at officers in a full-face veil.

The Times also reports that the family was obsessed with black magic, violence, and religious fever. The girls’ father, Adil Boular, 52, blamed the mother, telling the paper: “Whatever they have done so far they’ve done it to please the mother.

“I understand that my kids are not innocents [but] my daughters were failed by their mother. She was encouraging them – more than that, she was advising them on what to do.”

Deputy Assistant Commissioner Dean Haydon said: “This investigation started with Safaa, and her attempts to travel out to Syria, marry a Daesh fighter and support their terrorist activity. Having been prevented from travelling to Syria, she then set about plotting an attack in the UK but her plans were being covered by the counter terrorism network and security services.

“After Safaa was arrested and charged, her mother and sister tried to pick up where she left off. But again, working with the security services, we tracked their plans and stopped them before they were able to put them into practice.

“All three women were filled with hate and toxic ideology and were determined to carry out a terrorist attack. Had they been successful, it could well have resulted in people being killed or seriously injured. But thanks to the work of the security services and counter terrorism police, their plans never came to fruition.”