A conservation watchdog is backing two sites inside Brighton and Hove for a controversial multi-million sewage treatment works.

The Sussex Downs Conservation Board said Black Rock in Kemp Town was its preferred site for the urgently-needed plant, with nearby Lower Sheepcote Valley in reserve.

Brighton and Hove City Council has already ruled out building at Black Rock and said sites in Sheepcote Valley should not be considered.

Southern Water has identified eight sites for a sewage treatment works, urgently needed to meet European clean water guidelines.

The conservation board's planning committee will be told on Monday the plant should be built as close as possible to Brighton and Hove.

The board is backing environment groups and calling for third stage treatment at the new sewage works. Southern Water only proposes two cleansing stages for the 95 million litres of waste water generated in Brighton and Hove every day.

Planning officer Martin Small said: "It seems reasonable that waste water from Brighton and Hove is processed as close to the point of origin as possible. We would also like to see tertiary treatment."

The other six sites identified by Southern Water are: Ovingdean South; Upper Sheepcote Valley, Brighton; Brookside Farm, Newhaven; North Quay, Newhaven; Peacehaven East and Shoreham Harbour.

Ovingdean South is ruled out by the board because it is inside the proposed South Downs national park and Upper Sheepcote Valley because of the impact on the landscape.

Both the Newhaven sites are rejected partly because of the possible effect of pollution in the Seven Sisters voluntary marine conservation area.

Peacehaven East would be close to the proposed national park, while siting the plant at Shoreham Harbour would compromise the site as an alternative to building a football stadium at Falmer, opposed by the board.

The Environment Agency's Sussex Area Advisory group this week backed Lower Sheepcote Valley as the most promising option.

City council leader Ken Bodfish said: "The council's plans for Black Rock are important and will really revitalise that area of the seafront, a sewage works would kill it stone dead. To have it in an urban area such as Sheepcote is barmy."