An unexploded Second World War bomb has been found in London's River Thames near the start of Sunday's Oxford-Cambridge Boat Race, police said on Saturday.
"Police were called by a member of the public at approximately 1.50 pm (1250 GMT) on Saturday reporting what they thought to be World War Two ordnance on the Chelsea shoreline by Putney Bridge," said a Scotland Yard spokesman.
"Officers including the Marine Policing Unit attended. The item is currently submerged."
Thousands of people are due to line the banks of the Thames to watch the 163rd edition of the annual contest between the two British universities, which involves men's and women's races.
Police said they were working with the race organisers. The event is expected to go ahead as planned.