A man is due to appear in court later over an alleged plot to kill the prime minister, Theresa May.
The BBC understands Naa’imur Zakariyah Rahman, 20, from north London, is accused of planning to bomb Downing Street security gates and then attack the PM with a knife.
A second man, Mohammed Aqib Imran, 21, of Birmingham, is accused of the preparation of terrorist acts for allegedly planning to travel overseas.
They were both arrested on 28 November.
The pair are due to appear at Westminster Magistrates’ Court, in central London.
It comes a day after a security review said it was “conceivable” that the Manchester Arena bombing in May, in which 22 people were killed, could have been prevented.
But MI5 chief Andrew Parker told Mrs May and the Cabinet on Tuesday that about nine alleged Islamist terror plots have been foiled since March.