Prime Minister Gordon Brown is chairing a meeting of the Government's COBRA emergency committee as the Environment Agency warned of "extreme danger to life and property" in parts of Norfolk and Suffolk, while part of Kent, East Yorkshire and :incolnshire are also under flood alert.
Earlier, Environment Minister Hilary Benn told MPs: "A tidal surge of up to 3m [10ft] is making its way down the North Sea which could coincide with peak high tides.
"There is a risk of flood defences being over-topped on the coast and in tidal rivers, especially in East Anglia, particularly the Norfolk Broads and the coast south of Great Yarmouth including Lowestoft, and areas south of this as far as the coast of Kent."Experts said the surge was almost as high as the one which caused the 1953 floods in which more than 300 people died.
It is caused by a combination of north-westerly gales, low air pressure and high tides. Homes are being evacuated tonight in areas which are expected to be worst-hit.
High tide is expected around 7am in Norfolk.