Two of Brighton and Hove's beaches have been recommended for their excellent water quality in the new Good Beach Guide.

Brighton Kemp Town and Hove are recommended in the Marine Conservation Society's (MSC) guide after reaching European statutory water quality standards.

But there is no mention of Palace Pier and Portabello beaches, both of which have sewage outlets into the sea.

Preliminary sewage, meaning sewage which is partially treated, is constantly flushed into the sea from an off-shore pipe from Portabello, while the Palace Pier area contains a valve designed only for use in an emergency to prevent flooding in the city.

MSC coastal pollution officer Thomas Bell said he would "exercise caution for any beach with preliminary discharge", like Portabello.

He said: "The sewage isn't well treated. It's riddled with bacteria so you would want to exercise a great deal of caution if you were going to get into the water."

The data for the guide was provided by the Environment Agency, which did not provide information for Portabello or Palace Pier to the MSC.

An agency spokesman said it only monitored the bathing beaches classified 20 years ago and, with only one beach being monitored per town, Kemp Town was chosen because it was busier than Palace Pier.

Brighton-based director of Surfers Against Sewage Richard Gregory said he was amazed Kemp Town could be deemed more popular than Palace Pier.

He said: "We're hugely suspicious about the motives behind it not being monitored, especially when it's in the city centre."

He said he has seen a "flume of sewage" coming from the end of the pipe off Portabello towards Brighton and says the public should be told when Southern Water releases the emergency valve at Palace Pier.

To solve the problem, he wants the new sewage project planned for Peacehaven to include ultra-violet treatment to clean the sewage, similar to the one in Chichester.

A Southern Water spokeswoman said the Peacehaven project was vital to bring the water up to modern day standards and is designed to incorporate ultra-violet treatment, should there be a European directive to do so.

She added that the valve at Palace Pier has only been opened once, in 2001, and the discharge is not harmful because the sewage would be heavily diluted.