Police name two London attackers, say one investigated before

British police have named two of the three London attackers, adding that security services had previously investigated one of the militants who carried out Saturday's attack, but with resources scarce, he was not deemed enough of a threat to warrant close monitoring, police said on Monday.

In what was Britain's third attack in as many months, three men rammed a van into pedestrians on London Bridge before running into the Borough Market area, where they killed seven people and wounded dozens through stabbing.

All three attackers were shot dead by police, who made at least a dozen arrests in east London on Sunday and carried out further raids on Monday.

Police on Monday named two of the attackers as Khuram Shazad Butt and Rachid Redouane, adding that they were trying to identify the third.

Metropolitan Police assistant commissioner Mark Rowley said: "Inquiries are ongoing to confirm the identity of their accomplice."

Butt, a 27-year-old British citizen born in Pakistan, had already been investigated by police and Britain's domestic spy agency MI5.

Rowley said the investigation into Butt had begun two years ago but "there was no intelligence to suggest that this attack was being coordinated and the investigation had been prioritised accordingly".

"Work is ongoing to understand more about them, their connections and whether they were assisted or supported by anyone else," he added.

Redouane, 30, who went by the alias Rachid Elkhdar and claimed to be Moroccan or Libyan, lived in the same area of east London as Butt.

Police said on Monday they had released all 12 people arrested in the neighbourhood on Sunday without charge. However, police were investigating what appeared to be Molotov cocktails in the back of the van, Sky News reported.

Following the attack, Rowley outlined his blueprint to radically change Britain’s strategy to stop such attacks, saying the threat is now at a “completely different” level of danger.

He said the changes could cover police, MI5, communities, technology companies, the law and other policies.