London attack: Pakistan-origin man among three attackers

London: British police and security services had previously investigated one of the Islamist militants who carried out Saturday's attack in London, but with resources scarce, he was not deemed enough of a threat to warrant close monitoring, police said on Monday.

The news raise questions both about the police's judgement, and increases pressure on Prime Minister Theresa May, who three days before a national election is facing criticism for overseeing cuts to police during her years as interior minister.

In Britain's third Islamist attack in as many months, three men rammed a van into pedestrians on London Bridge before running into the Borough Market nightlife area, where they slit throats and stabbed people indiscriminately. Seven people were killed and dozens wounded.

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 morning.

Police named two of the three attackers on Monday and said they were trying to identify the third.

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

"However, there was no intelligence to suggest that this attack was being planned, and the investigation had been prioritised accordingly," police said.

Another attacker, 30-year-old Rachid Redouane, went by the alias Rachid Elkhdar and claimed to be Moroccan or Libyan, police said. He and Butt lived in the same area of east London.

One of Butt's neighbours, Ikenna Chigbo, told Reuters he had chatted with Butt - known locally as "Abz" - just hours before the attack on Saturday and said he appeared "almost euphoric".

"He was very sociable, seemed like an ordinary family man. He would always bring his kid out into the lobby."

Another neighbour, Michael Mimbo, told Reuters that Butt supported the north London football team Arsenal. One of the dead attackers has been pictured wearing an Arsenal shirt.

Mimbo said Butt had grown a longer beard and worn traditional Islamic dress more often over the two years he had known him, but showed no sign of radicalisation.

Police said they had arrested 12 people in the area, seven women and five men, and released two after inquiries.