The Islamists plan to blow up the gate of Downing Street and attack the building housing the British Prime Minister's Office with knives and suicide vests in order to assassinate Prime Minister Theresa May, believed to have been prevented by the UK security services.
The plot is said to have been hatched by two young Islamists who were arrested by gunmen last week after weeks of investigations by the Metropolitan Police, MI5 security service and the West Midlands Police Department.
They are 20-year-old Naimur Zakaria Rahman from north London and 21-year-old Mohamed Akib Imran from south-east Birmingham. However, although they are believed to have been inspired by the Islamic State, they are believed to have failed to obtain or manufacture explosives.
The two arrested were charged with preparing a terrorist act. They will appear before an investigator in London on Wednesday.
The British government ministers were briefed on the plan on Tuesday by MI5 Commander Andrew Parker.