London police: Eight arrests over Westminster attack

Police identify British man as assailant and arrest eight in probe into deadly attack near UK parliament.

The suspect of a deadly attack outside the UK parliament in London was British, Prime Minister Theresa May said, as police arrested eight people after several overnight raids across the country.

Police named the man as Khalid Masood on Thursday, saying he had a string of criminal convictions.

Masood, 52, was born in Kent to the southeast of London and had been most recently living in central England, London police said.

"Masood was not the subject of any current investigations and there was no prior intelligence about his intent to mount a terrorist attack," a police statement said.

"However, he was known to police and has a range of previous convictions for assaults, including GBH [grievous bodily harm], possession of offensive weapons and public order offences."

He had not been convicted previously for any terrorism offences, it said.

In a statement to the House of Commons on Thursday, May said Masood was once investigated by intelligence officers over concerns of "violent extremism". 

The Islamic State of Iraq and the Levant (ISIL) group claimed responsibility on Thursday for the attack. It said on its Amaq website the attacker "carried out the operation in response to calls for targeting citizens of the coalition" of countries fighting ISIL in Syria and Iraq.

It was not possible for Al Jazeera to independently confirm the claim, which did not offer any details of the attack or name Masood, casting doubt on whether there is any direct link between ISIL and the London killings.

Joseph Downing, from the London School of Economics, expressed scepticism over ISIL's claim.