British police on Monday named two of the three attackers who killed seven people near London Bridge late on Saturday and injured dozens more, and said one of them was previously known to the security services.

London's Metropolitan Police said one attacker was Khuram Shazad Butt, aged 27. Butt was previously known to police and domestic spy agency, MI5 and was a British citizen who had been born in Pakistan, the police said.

"However, there was no intelligence to suggest that this attack was being planned and the investigation had been prioritised accordingly," police said, without providing details on why Butt had come to the attention of law enforcement.

The second attacker was named as Rachid Redouane, aged 30, who also went by the identity Rachid Elkhdar and was not known to police. Redouane had claimed to be Moroccan and Libyan.

READ MORE: ISIL claims responsibility for London attack

Police said they were still working to establish the identity of the third attacker.

Both named men were from the east London suburb of Barking, where police raids began following the attacks on Saturday night.

Dozens were injured, 18 of them critically, in the attack that started on London Bridge, when the three attackers swerved a van into pedestrians then, armed with knives, rampaged through the nearby Borough Market, slashing and stabbing anyone they could find. The three men also wore fake suicide vests.

The three suspects were shot dead by police officers within minutes of launching the attacks.

The Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group claimed responsibility for the attack.

The London Bridge attack was the third in Britain in three months that ISIL has claimed, after the bombing in Manchester on May 22 and an attack in Westminster, London in March.

Ten people arrested in east London on Sunday in connection with the attack have been released without charge. Two additional addresses were searched on Monday.

Source: News agencies