Police have reportedly performed a controlled explosion near Westminster, less than a mile away from the scene of a terrorist attack which claimed the lives of four people.

The Metropolitan Police said officers found an unattended bag in Birdcage Walk, which runs between Westminster and Buckingham Palace.

It came less than two days after terrorist Khalid Masood killed four people by driving through pedestrians on Westminster Bridge and trying to storm Parliament.

A Metropolitan Police spokesman said: "Police are dealing with a suspect package in the area of Birdcage Walk. Officers remain at the scene."

The spokesman did not confirm whether a controlled explosion had been carried out.

The Met said on Twitter: "Unattended bag found Birdcage Walk/Horseguards was not suspicious. All cordons put in for safety being lifted. Thanks for your patience."

The reported explosion came during a BBC News live broadcast. Senior producer Pia Talbot tweeted: "Police say they've just carried out a controlled explosion within earshot of our live spot."

Sky News reporter Laura Bundock tweeted there was a "very loud bang close to security cordon where suspicious package found".

Masood is thought to have regularly attended a mosque in Birmingham, although security sources refused to discuss details because, they said, it was part of ongoing investigations.

Scotland Yard said eight people – five men and three women – had been arrested in London and Birmingham and were being held on suspicion on preparing terrorist acts.

In pictures: Westminster attack Show all 9 1 /9 In pictures: Westminster attack In pictures: Westminster attack An air ambulance lands after gunfire sounds were heard close to the Palace of Westminster in London PA wire In pictures: Westminster attack MPs wait until the situation is under control in Westminster. 'The alleged assailant was shot by armed police,' David Lidington, leader of the House of Commons, told the house. BBC News In pictures: Westminster attack Crowds gather in Westminster after shooting incident, which police are treating as terror attack BBC News In pictures: Westminster attack Police were also called to an incident on Westminster Bridge nearby AP In pictures: Westminster attack Early reports indicate the car, which mounted the pavement on Westminster Bridge and mowed into around a dozen people, was the same vehicle which then rammed into the railings of the Palace of Westminster, just around the corner Reuters In pictures: Westminster attack Security sources described the suspected assailant as a middle-aged Asian man, who is understood to have left the car before attacking a police officer with a seven-to-eight inch knife PA wire In pictures: Westminster attack Police have asked people to avoid the immediate area to allow emergency services to deal with the ongoing incident AP In pictures: Westminster attack One woman has died and a number of others, including the police officer, have been hurt, according to a junior doctor at St Thomas' Hospital Reuters In pictures: Westminster attack At least three gun shots were heard by those inside Westminster, and proceedings in the House of Commons have been suspended AP

Detectives are continuing to search a number of addresses in relation to the attack, including three properties in Birmingham, one in east London, and one in Carmarthenshire, Wales.

Isis claimed the attacker was a "soldier of the Islamic State" when it claimed responsibility for the attack.