A council is going door-to-door trying to persuade local residents to evacuate their homes before work begins on removing an unexploded Second World War bomb.
The Royal Navy was called to the King George V Dock in east London after the device was discovered early on Sunday morning.
It was identified as a German 500kg fused device, with police quickly setting up a 214-metre exclusion zone to ensure there is no risk to the public.
Newham Council said work on removing the bomb is expected to begin on Monday evening, although it is likely that all residents in the exclusion zone will need to be evacuated first.
Some residents refused to leave their homes when officials knocked on their doors in the early hours of Monday, but the council says it will continue its evacuation attempts throughout the day.
Once work has begun, the exclusion zone could then be extended to 250 metres, meaning more properties would need to be evacuated.
A council spokesman said: "Officers are assisting with a controlled evacuation of people in this exclusion area, a rest centre has been opened where bedding and refreshments are available for families who have been unable to stay with family or friends."
All flights out of the nearby London City Airport have been suspended, with more than 100 departures cancelled on Monday.
Among thousands of passengers affected, many Tottenham Hotspurs fans heading to Italy for a Champions League football match saw their plans thrown into disarray.
The north London football club advised any fans flying to Milan to "contact their airline as soon as possible", ahead of the club's match against Juventus on Tuesday evening in Turin, Italy.
The airport originally had eight flights scheduled to Milan on Monday, but all were suspended or cancelled while police called in specialist officers to the dock.
Spurs fan David, 52, was booked to fly to Milan on Monday before taking a connecting train to Turin ahead of the Champions League away match.
He discovered on Monday morning that his flight was cancelled, however.
British Airways has now booked him onto a new flight on Tuesday, he says, but he is disappointed he has lost a hotel night in Turin.
"I woke up this morning to discover that the airport's shut and all the flights are cancelled," said David, who has travelled abroad to see Spurs play several times before.
"There's no sense of 'you're out of pocket for a night in a hotel."
In a statement, Scotland Yard said: "The device has been examined by Met Police and Royal Navy dive teams and is confirmed as being a 500kg tapered-end shell, measuring approximately 1.5m.
"It is lying in a bed of dense silt and the first stage of the removal operation is to free the shell from the silt so that it can be floated for removal.
"The operation to remove the ordnance is ongoing in partnership with our colleagues in the Royal Navy. The timing of removal is dependant on the tides, however, at this stage we estimate that the removal of the device from location will be completed by tomorrow morning."