The wind farm, which would consist of 11 turbines built just inside the old breakwaters in the harbour, will be in the centre of waters used by Britain’s new National Sailing Centre (NSC), which has been chosen as the site for the Olympic regatta.

The problem is that the huge wind turbines, the tops of which would rise to 100 metres above sea level, will affect the flow of air around them and cause turbulence that could make world-class sailing impossible.

The Royal Yachting Association (RYA), the governing body of sailing in Britain, which runs the new Portland venue, believes that the turbines will affect almost all of the five proposed racing areas that would be used at the Games. Its research suggests that the structures would cause a “wind shadow” stretching up to 1,600 metres behind each one.

Richard Ottaway, the Conservative MP for Croydon South, who is a member of the Council of the RYA, said he found it hard to believe that Powergen would want to be associated with anything that could harm London’s Olympic bid. “As far as the Olympic bid is concerned, we have got to send the message to the rest of the world that the whole country is behind it and that wouldn’t be the case if big business is saying ‘forget the Olympics, we’re trying to make some money’,” Ottaway said.

He added that the proposed wind farm causes what he called a “conflict in the public interest”. He said: “It is not just the Olympics — you could presumably stop the turbines during the Olympics. Portland is the best place for this type of yachting in the UK and there is a permanent demand for yachting facilities there which will be ruined by this wind farm.”

Indeed, the RYA is concerned not just for the Games but for the long-term viability of the NSC, the facilities of which are being built at a cost of about £8 million. The NSC got the go-ahead only six months ago and is funded by Sport England from National Lottery funds, the South West Regional Development Agency and other local bodies.

Even if the Olympic bid fails next year, the RYA is keen to ensure that its facility remains viable as a world-class centre that will attract national and international championships for years to come. “The RYA is not against wind farms but there is a real potential for conflict between the activities of the sailing academy and a wind farm,” John Derbyshire, the RYA’s racing manager, said. “If further studies find the turbines are going to have an impact on the sailing, whether that is a real or a perceived impact, then we will be against that.”

Powergen said that its Portland project is at an early stage and the company emphasised that it is keen to take account of all local interests, not just those of the sailing community. Jonathan Smith, a Powergen spokesman, said that there was still plenty of room for manoeuvre.

“We are not going to do anything that’s going to harm anybody’s business or potential business. Sailing is one of many, many things that we’ve got to look at in the years to come — it’s not as though we are building the wind farm tomorrow and haven’t consulted anybody,” Smith said. “We are keeping an open mind — we don’t know for sure whether this is a viable wind farm site. Whether it’s got enough potential to make it attractive, we don’t know yet.”

Smith said Powergen believes that more detailed studies of the effects of turbines on wind conditions are required before estimates such as those made by the RYA can be reliably made. He said that the company, which has already installed wind measuring masts on the breakwaters, is hoping to try to “model” the impact on sailing during the course of future research.

The Portland wind farm would cost about £20 million to build and would generate about 20 megawatts of electricity per year. This would be enough for 15,000 homes, roughly equivalent to the annual domestic power needs of Weymouth and Portland. The Government has recently set out its strategy for the development of offshore renewable energy and has set a target of 10 per cent of Britain’s energy resources to be produced by renewable resources by 2010