Thousands of lives and homes are at risk from a devastating storm which can hit the coast once in every 200 years.

More than 35,000 homes in Sussex are in danger of being swept away because flood defences could not cope with the kind of storm which experts say could hit the county within the next 54 years.

Most of the coast has sea defences in place to cope with fairly serious storms but if a one-in-200-year storm hits, thousands of homes in high-risk areas, including Selsey, Bognor, Littlehampton, Shoreham, Newhaven, Seaford, Pevensey Bay and Bexhill, could be swamped by a torrent of fast-flowing, deep sea water. No one can predict when such freak weather might happen again but the latest advice by environmental experts says Sussex should expect a storm of this magnitude by the year 2060.

The devastating impact of a tidal surge, which would swamp vast swathes of the Sussex coast, were revealed when the Environment Agency objected to a planning application for a house in Ormonde Way, Shoreham Beach.

Adur district councillors were advised not to agree to the plans because the site was in a high flood risk zone and were warned of the risk of a freak tidal surge.

A report to the council's planning committee said: "The existing flood defences provide protection to a level of 4.2m and if overtopped, it is likely the site would be subject to deep, fast-flowing waters with no opportunity for safe, dry access to land outside the flood risk area."

Devastating storms are listed in categories according to the probability of a combination of freak weather conditions occurring at the same time.

Coastal flood defences are being bolstered by a £30 million building plan by the agency which would protect Sussex from the kind of storm which devastated the east coast of England in 1953 - leaving hundreds dead - which was caused by swelling tides and high winds and happens about once a century.

But steadily-rising sea levels caused by global warming are increasing the chances of a deadly surge in the water.

This, combined with the kind of freak weather which breaks about once in every 200 years, could boost storm surges by more than 4.7m, swamping the areas around Shoreham and Newhaven.

The results of a storm of that magnitude were recorded in the Great Storm of 1703 which killed hundreds, destroyed thousands of homes from East Anglia to Bristol and killed 8,000 sailors.

If a deadly storm hits, 35,000 homes in high-risk areas in Sussex could be flooded.

Andrew Gilham, the Environment Agency's flood risk manager for Sussex, said it was not predicting a date for the next big storm but planning for the worst-case scenario.

But Mr Gilham said there would come a time when the "unstoppable forces of nature" would win the battle.

He said: "The situation is changing and getting worse. If we stopped building defences we would soon see significant flooding, which is why we are constantly spending time and money on improvements.

"The risk of a severe storm is relatively low but it is something people need to be aware of."

Nick Gibb, MP for Bognor, said it was crucial the agency was given as much money as it needed to carry out defence work.

He said: "In general sea defences are very good but there are certain areas where more has to be done."