Government appointed experts have warned that a barrage built to harvest the tidal power of the Bristol Channel could cost the region hundreds of millions of pounds in lost business and lead to thousands of job losses.

Feasibility studies are being carried out into ten different schemes designed to harness the energy from the estuary.

According to opponents the consultants in charge of the study into the economic impact of the barrage have warned that a barrage from Weston-super-Mare to South Wales would cripple the West's economy and badly affect the shipping industry based around Avonmouth and Gloucester docks.

Mike Johnson, of the Gloucester Harbour Trustees, said: "Building a barrage would create construction jobs in the short term, but these would go as soon as it was finished.

"Even if it got the go-ahead, a barrage might not be built for many years, but the job drain could start as soon as it got the green light if ship-owners began to lose confidence in the retention of access to the Severn Estuary ports.

"We would need more reassurance than we have received so far that Gloucester could be assured of its survival as a commercial port behind a barrage."

A shortlist of three schemes will be published in January but many believe a barrage – which would cost £15 billion and take a decade to build – is a already one of the leading contenders.

But according to the Stop the Barrage NOW campaign, during meetings organised by the Severn Tidal Power Feasibility Study Group a team of civil servants based in the newly-formed Department of Energy and Climate Change painted a worrying picture about the impact of the barrage.

Analysts from consultants DTZ, have been given the job of carrying out an Economic Impact Assessment. They told the various meetings that a barrage would cost thousands of jobs and hundreds of millions of pounds to the regional economy.

When contacted by the Western Daily Press the consultants and government officers at the DECC were not prepared to comment until the report is published.

The chief executive at Bristol Port Company Simon Bird, said: "Thousands of families in the South West rely on local ports and the maritime industry for their livelihood. A Severn Barrage would be an absolute disaster for our business and could lead to thousands of jobs being lost in the port and associated industries."

He added: "Bristol Port supports jobs for over 7,500 haulage workers, crane drivers, gantry operators, boatmen, tug operators and warehouse staff.

"This DTZ report confirms our worst fears, so why, as one of the ports concerned, are we not being allowed to see it?

"We've already had cust- omers and suppliers asking us about this report and the prospects for our port. If the Government cares about Bristol and the South West surviving the economic downturn, they need to make clear they are scrapping all barrage plans in favour of alternative renewable technologies."

Doug Naysmith, Labour MP for Bristol North West, said: "It would be great if we could use the power from the Severn but this is the third time a study has been carried out.

"Each time the effect on shipping in the channel has been ignored.

"Shipping is vital for the region's economy and building a lock in the middle of the barrage would probably prove too costly."

Dale Vince, a leading exponent of green energy, this week wrote to the prime minister to back the scheme. He is backing plans for a ten-mile dam which could generate enough green electricity to supply four per cent of Britain's power needs.

Dale Vince, the founder of Stroud based Ecotricity and one of the UK's biggest providers of green electricity, said: "We should build the barrage using public money.

"Each year, once the barrage is completed, instead of giving cash grants to the fuel poor, give them free fuel instead."

He believes the Government could use the barrage to insulate the UK from future rises in fossil fuel prices.