Two men are due in court on terror charges on Wednesday after reportedly plotting to assassinate the Prime Minister.
The alleged plan is said to have involved launching a bomb attack on the security gates outside Downing Street before stabbing Theresa May.
Details of the plan were reportedly given to the Cabinet on Tuesday by the head of MI5 Andrew Parker in a briefing in which he revealed that total of nine Islamist terrorist plots have been thwarted in the UK over the past year.
The Prime Minister's official spokesman declined to discuss the details of the attacks but several newspapers later reported that two young men arrested in London and Birmingham last week had been plotting to kill the Prime Minister.
The Metropolitan Police would only say that Naa'imur Zakariyah Rahman, 20, and Mohammed Aqib Imran, 21, were due to appear in custody at Westminster Magistrates' Court on Wednesday charged with planning terror attacks.
Rahman, from north London, is charged with preparing acts of terrorism and assisting Imran in terror planning.
Imran, from south-east Birmingham, is charged with preparing acts of terrorism.
Mr Parker's Cabinet briefing came on the same day that a review of a string of UK terror attacks earlier this year revealed that the Manchester Arena bomber was known to MI5 and his attack, in which 22 people died, could have been stopped "had the cards fallen differently".