London City Airport has been closed after a 500kg World War Two bomb was found nearby in the River Thames.
The airport will be 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 pre-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 dependant on the tides, however, at this stage we estimate that the removal of the device from location will be completed by tomorrow morning."
According to the airport's website, a total of 261 arrivals and departures had been scheduled for Monday.
"All flights today are cancelled but some airlines have moved their flights to other airports - CityJet to Southend and Alitalia to Stansted", the airport said.
Passengers have been told not to travel to the airport as the terminal is closed and to contact their airline.
"The airport is cooperating fully with the Met Police and Royal Navy and working hard to safely remove the device and resolve the situation as quickly as possible."
Members of airport staff are on Hartmann Road, the main route to the airport, to help redirect people.
Airlines using London City Airport include British Airways, Flybe, CityJet, KLM and Lufthansa, with flights to domestic and European city destinations.
Police said a 214-metre exclusion zone had been set up and properties inside were evacuated.
A rest centre has been opened by Newham Council to provide bedding and refreshments for families who have been affected
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