British police have detained a number of people during early morning raids in east London as part of an investigation into an attack that killed seven people and injured around 50 on Saturday night.
In the third major militant assault to hit Britain in less than three months, attackers rammed a van into pedestrians on London Bridge before stabbing revellers in nearby bars.
UK Prime Minister Theresa May will chair a meeting of the government's emergency response committee on Monday to discuss the response to the attack which comes ahead of a national election on Thursday.
Police had already arrested 12 people in the Barking district of east London over the weekend and said they had entered two premises in Newham and Barking at 3:15am (local time) and detained "a number of people".
Residents said they heard loud bangs and gunshots.
Police said searches were ongoing at both addresses.