British authorities have foiled a terrorist plot by two Muslim men to assassinate Prime Minister Theresa May, according to a media report on Wednesday.Police believe the plan was to launch some sort of improvised explosive device at Downing Street, where the prime minister’s residence is located, and attack and kill the premier in the ensuing chaos, Sky News quoted its sources as saying.Two men – Naa’imur Zakariyah Rahman, 20, from north London and Mohammed Aqib Imran, 21, from south-east Birmingham – were arrested last week by armed police and charged with “preparing acts of terrorism”. They will appear at the Westminster Magistrates Court on terror charges.Sky News reported this was the latest in a number of terror plots that police and the MI5 intelligence service foiled this year. The head of MI5, Andrew Parker, briefed cabinet ministers on the latest plot because of the “seriousness of what they believed they have uncovered”.“It is in essence an extreme Islamist suicide plot against Downing Street…This is something which has been pursued over several weeks at least by Scotland Yard, MI5 and West Midlands Police,” the report said.MI5 said on Tuesday it had prevented nine terror attacks in the UK in the past year.Downing Street, located in the heart of London, is well protected with fortified gates and armed police officers. Better security measures were introduced in the area in the 1970s and the 1980s, largely because of threats posed by Irish republican groups.In 1991, the IRA carried out an attack on the premier’s residence at 10 Downing Street with a home-made mortar. The bomb landed in the back garden though the then prime minister, John Major, escaped unhurt.Britain has witnessed several high profile terror attacks by the Islamic State this year. In March, five people were killed when Khalid Masood drove a car into pedestrians on Westminster Bridge and stabbed a policeman guarding Parliament.In May, 22 people died when suicide bomber Salman Ramadan Abed targeted concert-goers at Manchester Arena. The next month, 11 people were killed terrorists used vehicles and knives to attack people at London Bridge. In September, an attempt to bomb a London Tube train at Parsons Green station failed.