British security services have foiled an alleged conspiracy to kill British Prime Minister Theresa May, according to the country's media.
The London Metropolitan Police issued a statement on Tuesday announcing the arrest of two men last week for terrorism crimes.
One of them, Naa & Imam Zakariyah Rahman, 20, is accused of planning to bomb the doors of her Downing Street residence in central London before attacking May with a knife at the subsequent carnage, The Times reported. The British anti-terrorist police arrested him in a raid on November 28.
The other suspect, Mohammed Aqib Imran, 21
It is not yet clear what extremist group, if any, the couple was acting on behalf of.
Britain has suffered four attacks claimed by Islam State militant group (ISIS) this year: a car bomb attack on the Westminster Bridge in March, a suicide bombing at a concert by Ariana Grande in Manchester in May, an attack with van-biting and a knife on the London Bridge in June and a partial explosion on a subway train in West London in September.
The attacks killed 35 people and wounded dozens more. In another extremist attack, a man ran over Muslims in front of a mosque in north London in June, killing one.
Former Prime Minister Margaret Thatcher introduced fortified doors at the Downing Street residence in 1989 as a security measure. The Irish Republican Army, or IRA, threw a mortar in Downing Street in 1991, but caused no damage. The group previously targeted Thatcher at her conservative party conference in 1984. The bomb blast missed her but killed five people, including one of her British political colleagues. 
Britain is facing one of the worst cases of internal radicalization in Europe, along with France. The head of the British national security service MI5 warned in October that the threat of jihadist attacks in Britain was at its "highest rate" in his three-decade career.
British security services have thwarted nine attack plans this year, including one targeting May. In the four years since British soldier Lee Rigby was shot dead in south-east London, MI5 and police have foiled up to 22 plots by Islamists and right-wing extremists.