The airport has been shut all day and all flights cancelled, affecting up to 16,000 passengers, a spokeswoman said.
The bomb was found at George V Dock on Sunday during planned work at the east London airport, police said.
Families in the area have been evacuated with the exclusion zone set to be widened when specialists begin removing the device.
The airport was shut at 22:00 GMT on Sunday. The Met Police said it was working with the Royal Navy to remove the bomb.
A statement issued by the Met said: "The timing of removal is dependent on the tides, however, at this stage we estimate that the removal of the device from location will be completed by tomorrow morning.
Information Source www.bbc.com 2018.02.12
