Glasgow and other major cities around Britain are at grave risk from catastrophic flooding because flood defence planners have failed to take into account the latest evidence on rising sea levels.

New research by the Met Office has revealed that the UK government's official predictions for sea level rise are out of date - because they do not include the effects of melt water from the massive Greenland ice sheet.

The situation is so serious that the Environment Agency is being forced to carry out a review of its flood defence plans for London. Contingency plans for other major low-lying cities like Glasgow, Liverpool, Bristol, Newcastle and Hull will also have to be re-evaluated.

The extent of the problem was revealed yesterday by Dr Jason Lowe, a senior Met Office climate scientist who has just completed the most detailed study yet carried out into the likely rates of sea level rise around Britain.

Dr Lowe said that whereas the current flood defences are based on predictions for a sea level rises of just under one metre this century, the average water levels around Britain could rise by as much as two or three metres. The effects of "storm surges" could push water levels up further to four or even five metres.

If that happened the present Thames Flood Barrier, designed to cope only with rises of just over a metre, and many sea defences around the Scottish coast would be useless.

Dr Lowe, speaking at the British Association for the Advancement of Science's conference, said all major conurbations on estuaries or in coastal areas could be vulnerable.

"Until we can rule out these larger rises - or either rule them out or confirm them - we think it is worthwhile planners looking at least at the vulnerability to these increases," he said.

A Scottish Government spokeswoman said current flood defence planning was based on predicted sea level rises of 60cm this century.