A terror plot to assassinate British Prime Minister Theresa May after detonating an explosive device at her Downing Street office has been foiled by the country's security services, media reports said on Wednesday.
Two men were taken into custody last week in connection with the plot, but news of the arrests came when an official report was released, The Guardian newspaper reported.
A Sky News correspondent said there was an "extreme Islamist suicide plot against Downing Street''. Other reports also called it an 'Islamist' plot, but did not say if the two were connected to Islamic State or any other organised terror group.
The two men, 20-year-old Naa'imur Zakariyah Rahman and 21-year-old Mohammed Aqib Imran, appeared at Westminster Magistrates' Court in London on Wednesday and faces terror charges following their arrest by counter-terrorism officers on 28 November. They have been remanded in custody till 20 December.
At a brief hearing, the court was told that Rahman had ''planned to detonate'' a bomb at Downing Street gates and in the ensuing chaos try to kill May with a knife. He is charged with the preparation of terrorist acts and is also charged with assisting another man to prepare separate acts of terrorism. Imran is accused of allegedly planning to travel overseas for the preparation of acts of terror.
The latest plot emerges as a new report released this week found that the UK's security services could possibly have prevented a suicide attack at the Manchester Arena in May. Bomber Salman Abedi killed 22 people when he blew himself up outside an Ariana Grande concert in Manchester.
Barrister David Anderson, who was asked to conduct an independent investigation, said Abedi had been on MI5's radar but that his ''true significance was not appreciated at the time''. After reviewing the security services' actions in relation to four terrorist attacks in the UK this year, he concluded, ''It is conceivable that the Manchester attack in particular might have been averted had the cards fallen differently.''
His report also noted that the Pakistani-origin ringleader, Khuram Butt, of the terror attack on London Bridge in June had been on the security services' radar for two years. The 27-year-old had been watched by MI5. Butt was involved in ''high risk extremist activity'', according to intelligence initially received by MI5 but the assessment was downgraded and he was believed to have turned his attention to travelling overseas instead.
Butt appeared on the security radar a number of times and was on bail for fraud on June 3 when he, Youssef Zaghba and Rachid Redouane killed eight people in a knife and van attack.
Internal reviews into the police and MI5's handling of the four terrorist ?attacks in Britain this year also revealed one of the London Bridge attackers had been under active investigation by the Security Service.
The Westminster Bridge attacker, Khalid Masood, had also watched suicide attack videos on YouTube in the days before he carried out his assault.
Britain has witnessed several terrorist attacks on its soil this year, including ones at an Ariana Grande concert in Manchester and in London's Westminster and London bridges. The MI5, Britain's domestic counter-intelligence agency, said nine terrorist plots had been thwarted in the last 12 months.