Two more men have been arrested in connection with the Parsons Green bombing, taking the total to five, Scotland Yard said.
Men aged 30 and 48 were detained during a raid by counter-terrorism officers at a home in Newport, South Wales at around 5.10am on Wednesday.
A third man, 25, who was arrested at a separate address in Newport shortly after 7pm on Tuesday. Two other suspects detained on Saturday remain in custody.
Commander Dean Haydon, head of the Met Counter Terrorism Command, said: "This continues to be a fast-moving investigation.
"A significant amount of activity has taken place since the attack on Friday.
"We now have five men in custody and searches are continuing at four addresses.
"Detectives are carrying out extensive inquiries to determine the full facts behind the attack.
"We anticipate that the searches will take some days to complete and may cause further disruption.
"However, it is important that we continue with these searches and I'd like to thank all those affected for their support, patience and cooperation."