A body retrieved from the Thames river is believed to be that of a French national who was killed in the attack over the weekend.
A third French citizen has died following Saturday's attack on London Bridge, President Emmanuel Macron said on Wednesday, taking the overall death toll to eight.
"We have had the latest toll confirmed this morning, which is three people dead and eight injured on the French side," said Macron, who was speaking during a joint news conference with Danish Prime Minister Lars Lokke Rasmussen.
British police hunting for a Frenchman missing since Saturday's attack said earlier that they had found a body in the River Thames.
The police said the formal identification of the body had not yet taken place but that the family of the missing Frenchman, 45-year-old Xavier Thomas, had been informed of the discovery.
"Detectives investigating the terrorist attack in London Bridge on Saturday, 3 June, can confirm the number of people that were killed as a result of the attack is now eight," a spokesman said.
Le Parisien newspaper named the second Frenchman to die in the attack as 36-year-old Sebastien Belanger, while the other French victim was 27-year old Alexandre Pigeard.
Police also confirmed that another person had been arrested in connection with the attack.
"Detectives investigating the London Bridge terror attack have carried out a search warrant at an address in east London in the early hours of Wednesday," police said in a statement.
"A 30-year-old man was arrested on suspicion of the commission, preparation or instigation of terrorist acts," police said.
A 27 year old man was arrested on Monday. Prior to that 12 people had been arrested, but all of those 12 were subsequently released.