The Marine Conservation Society tested 754 beaches at the end of last summer for sewage and dirt in the water.

The number recommended for swimming was only 403, 113 fewer than the previous year.

The remaining beaches could be dangerous for swimming at some point of the year because of sewage and other bacterial flowing into the sea.

The Marine Conservation Society said the fall in water quality was down to one of the wettest summers on record last year.

The rain and flooding led to an increase in bacteria and viruses in bathing water, coming from a variety of sources such as agricultural and urban run-off, storm waters, plumbing misconnections, septic tanks and dog waste.

The pollution can give bathers ear, nose and throat infections and even gastroenteritis, the Marine Conservation Society said.

The Met Office has warned that wet summers could become more frequent.

The MCS said that therefore infrastructure need to be updated so that during floods sewage does not flow into the sea.

The also called for reduced pollution from farms and urban areas, ahead of tougher EU rules on water quality coming in from 2015.

MCS coastal pollution officer Rachel Wyatt said: "We have recommended fewer beaches in every English region and in Wales and Scotland. In England, the north west and south west were particularly badly hit with the fewest number of recommended beaches for at least a decade.

"Action must be taken now. With stricter bathing water standards from 2015 and summers that appear to be getting wetter, the iconic image of people bathing off golden beaches could be at serious risk.

"There is no simple solution to sewage and animal waste reaching our seas. However if the water industry, communities and local authorities recognise that there is a problem and begin to work together to find answers that would be a significant start."

The MCS said there were some promising local partnerships working together to identify problems and start trying to fix them, but in too many places there was an "out of sight, out of mind mentality" over water pollution.

The situation is a turn around from last year, when a record number of beaches were given the top "recommended" award for their water quality.

The South West saw a number of its previously recommended beaches fail last year, including Plymouth Hoe East and West, Shaldon and Exmouth in Devon, East Looe and Bude Summerleaze in Cornwall and Charmouth West in Dorset.

In the North West, just three beaches are recommended for excellent water quality in the new guide, with popular beaches at Blackpool North and South failing to meet even the basic mandatory standards.

But Blackpool central and nearby St Anne's and St Anne's North beaches improved their water quality to reach the mandatory standard last year.