Three women from London, including a mother and daughter, were charged on Wednesday with preparation of a terrorist act and conspiracy to murder, police said.
Khawla Barghouthi, 20, of northwest London, Rizlaine Boular, 21, of central London, and her mother Mina Dich, 43, of southwest London, are due to appear at Westminster Magistrates' Court on Thursday, the Metropolitan Police said.
The three were arrested last month.
Britain has been on its second-highest alert level of "severe" since August 2014, meaning an attack by militants is considered highly likely.
(Reporting by Subrat Patnaik in Bengaluru; Editing by Alison Williams)