WILDLIFE on the Firth of Forth is being put at risk because raw sewage is being allowed to flow directly into its waters, a leading conservation charity warned today.

The future of eider ducks, kingfishers and dippers on the estuary is being endangered by a lack of investment in the water industry, according to the Royal Society for the Protection of Birds.

The problem has been recognised by the Scottish Environment Protection Agency (SEPA), but - despite calls from the RSPB for extra funding - the Scottish Executive says the industry must find the cash to tackle the issue itself.

The main threat is to eider ducks, which are found on islands around the Forth bridges such as Inchcolm and Inchmickery, and only breed in coastal areas such as the Firth of Forth.

Kingfishers and dippers are sometimes seen in the estuary, but their chances of becoming established in the area are being hampered by the sewage risk.

Andrea Johnstonova, fresh water policy officer for the RSPB, said: "Eider duck are quite sensitive to this kind of pollution. Also, if the water quality was improved, we might see more species come back to the Firth of Forth, such as kingfishers and dippers.

"What has happened is that there has been a lot of investment in the sewage treatment works, but not in the combined sewage outflow pipes.

"Because of this, if there is a heavy storm and there is a lot of more water than usual, some raw sewage can be washed away and ends up in the Firth of Forth."

SEPA has identified the Firth of Forth as a priority area where action needs to be taken on the problem, and an agency spokeswoman added: "Investment is desirable, but it is a long-term issue."

The Executive said there were no plans to give extra funding to Scottish Water, but that water rates were set at a level which should allow the industry to make such improvements.

An Executive spokeswoman said: "Ministers are requiring Scottish Water to improve the quality of 530km of rivers and coastal waters.

"Scottish Water will be funded to reduce sewage discharges into rivers - improving the environment for birds and plant life."

Athol Duncan, director of corporate affairs at Scottish Water, said £280 million has been invested in upgrading other parts of the region's water network.

But he said the improvements were only the tip of the iceberg and that further investment was needed.

He added: "We are planning the 2006-10 investment period, which will involve further improvements to the water and waste water services in Edinburgh and Lothians.

Scottish Water is committed to working with organisations like the RSPB."