LONDON, Aug. 3 (Xinhua) -- An 18-year-old who became one of the youngest women to be convicted of terrorism offences in Britain was Friday sentenced to life in prison with a minimum of 13 years.

A jury found that Safaa Boular plotted with her partner, Naweed Hussain, an Islamic State (IS) militant, to launch a grenade and bomb attack on the British Museum in Bloomsbury, central London.

Boular, of Vauxhall, London, was also found guilty of attempting to travel to Syria to join terrorist IS.

She was the final member of her terror cell to be sentenced at the Old Bailey, after the convictions of her mother, Mina Dich, 44, her older sister, Rizlaine Boular, 22, and the family friend Khawla Barghouthi, 21.

Judge Mark Dennis QC rejected claims she had entirely renounced her Islamist views and downplayed the extent grooming played in her radicalisation.

An Old Bailey jury found she had planned to die in a suicide bombing in Syria, but when that was not possible, she hoped to attack the British Museum.

Their plans were uncovered by online M15 role-players and the Boular family home in Vauxhall, south London, was bugged.

Boular handed the baton to her older sister when she was in custody for trying to travel to the war zone.

Passing sentence, Judge Dennis told Boular her views were "deeply entrenched" and "she was old enough to make her own decisions and her own choices."

"However much she may have been influenced and drawn into extremism, it appeared she knew what she was doing and acted with open eyes," he said.