Image copyright PA

A teenager has been found guilty of plotting a terror attack on the British Museum in London with Britain's first all-woman cell.

Safaa Boular, 18, of Vauxhall, London, has become Britain's youngest convicted female Islamic State terrorist.

A jury at the Old Bailey found her guilty of two offences of preparation of terrorism acts.

She was also found guilty over an earlier attempt to travel to Syria for terrorism.

Boular was accused of planning to travel to Syria to join IS militants and later preparing to carry out a terrorist attack in London after her fiancé, an Islamic State fighter, died.

Image copyright Julia Quenzler

Her sister Rizlaine 22, of Clerkenwell, London, has already admitted planning a knife attack on London and their mother Mina Dich, 44, has pleaded guilty to assisting her.

Boular will be sentenced in around six weeks time.

During her trial, the court heard how Boular - then 17 - plotted a gun and grenade attack at the British Museum.

The sisters and Dich discussed their plans using Alice in Wonderland coded language, with Rizlaine as the Mad Hatter.

Image copyright Metropolitan Police Image caption Boular had originally hoped to travel to Syria and marry IS fighter Naweed Hussain

Aged 16, Boular was radicalised online in the wake of the 2015 Paris terror attacks.

She met IS fighter Naweed Hussain on Instagram and after three months of chatting, she declared her love for him with an online marriage ceremony.

The court heard how she had wanted to join Hussain in Syria, but her plan was thwarted when British security services became involved and confiscated her passport.

Boular told the police about Hussain and security services deployed officers to pose as fellow extremists and speak to the pair online.

On 4 April 2017, it was a security services officer, posing as an IS commander, who told Boular that Hussain had been killed in a drone attack.

The prosecution claimed this only strengthened her determination to carry out an attack in the UK.

Boular went on to tell officers posing as extremists about plans for an attack and on 12 April, she was charged with preparing terrorist acts in Syria.

Image copyright Met Police Image caption Mina Dich (left) and her daughter Rizlaine Boular, have both plead guilty to terror charges

Despite being in custody, Boular continued to talk to her sister and mother about an Alice in Wonderland-themed tea party - code for an attack.

In one call Boular complained: "Mate, you guys are partying without me."

Rizlaine and Dich carried out reconnaissance of major landmarks in Westminster and bought knives and a rucksack, the court heard.

They were arrested on 27 April, the date of the planned attack, along with friend, Khawla Barghouthi.

Counter-terrorism coordinator Dean Haydon said social services were called in to act back in 2016.

"As a family unit, they are pretty dysfunctional. There was a major safeguarding issue we had to manage. It did involve social services, local authorities, schools, education and family courts trying to safeguard the wider family," he said.

"But despite all that activity it was quite clear Safaa was still continuing with her attack plans."