Media playback is unsupported on your device Media caption George Ferguson said there were better ways of using the barrage technology

A new barrage across the Severn Estuary would damage the Welsh economy, Bristol's elected mayor has said.

George Ferguson said the barrage would have a detrimental impact if trade at the port of Avonmouth is affected as a result of the proposed £30bn project.

He has also opposed the Welsh government buying Cardiff Airport.

Campaigners for the barrage claim it could provide 5% of the UK's electricity and create thousands of jobs.

Mr Ferguson told BBC Sunday Politics Wales he was worried the barrage would prevent or slow down ships entering Avonmouth.

He said: "I think it's in the interest of the whole region that we have a successful port in the Severn of which our port on Avonmouth is a successful port.

'Much better ways'

Image caption Bristol mayor George Ferguson said a barrage would bring little economic or environmental benefit

"It's as close to Wales as dammit and I think if the trade at that port is damaged it damages us all."

Mr Ferguson became Bristol's first directly-elected mayor last November.

He is an independent and he has responsibility for leading the council's services and its £1bn-a-year turnover.

He said he did not see much economic or environmental benefit from a barrage.

"I think there are much better ways of using tidal and other forms of power in the Severn Estuary," he said.

"And there are much better ways in terms of the technology. We could develop a technology within in the Severn Estuary, within the south west and south Wales which we could export to the rest of the world."

Huge road infrastructure

But campaigners for the Severn barrage claim it could provide 5% of the UK's electricity and create thousands of jobs.

You can't export barrages, they are a pretty basic technology, they are a one hit George Ferguson, Mayor of Bristol

Professor Brian Morgan, a member of Hafren Power's regional board, the firm behind the scheme, said Mr Ferguson's comments were "preposterous".

He said: "Wales needs the infrastructure and investment. It's a fantastic opportunity. It will be a tourist attraction in itself and there'll be spin-off jobs created."

Stephen Doughty, MP for Cardiff South and Penarth, told Sunday Politics Wales he had an "open mind" about the barrage.

He said: "Obviously climate change is a key challenge as well as our future energy needs but there are a lot of unanswered questions about the barrage from the proponents - in terms of the engineering, in terms of the impact on ports.

"For example, would it affect Cardiff ports as well and I think they need to be answered before we move on any further in that debate."

Alun Cairns, the Vale of Glamorgan MP, said a barrage would mean huge road infrastructure through his constituency and a sub-station would need to be built in Barry.

He said: "These are some pretty major issues that need to be overcome by any developer of a barrage.

"We don't know if the money is available yet, we don't know how long it would take, it would need a hybrid bill in Parliament - that would take some sort of time.

"So by all means let's not dismiss it out of hand, let's have a look at it but I think there are some pretty big hurdles in front of any developer."

However, Mr Ferguson said: "You can't export barrages. They are a pretty basic technology, they are a one hit, while if we develop lagoons, if we develop other forms of tidal and wave and other ways of extracting the energy from the water and the wind then I think we've got a great potential export trade."

He described south west England and south Wales as "a single region" and he wanted to hold discussions with the Welsh government and some councils to explore future collaboration.