Environmental campaigners say plans a massive windfarm off the Sussex coast will cause “heavy” damage and disruption to the South Downs National Park.

The South Downs Society has called for E.ON to provide a “substantial package of environmental improvements” to mitigate the damage done in the laying of miles of underground cabling.

The energy giant wants to build the turbines that would create enough electricity to power 450,000 homes.

It will require miles of cabling that will run from the sea to Bolney substation.

The society said it wants E.ON to make a “big financial contribution” to a range of environmental packages in return for its support of the Rampion project.

The society said it has given its “qualified” support for the wind turbines – but at a price.

It wants the energy company to move existing “unsightly” overhead power lines underground and clear the old Shoreham cement works nearby.

Society chairman Robert Cheesman said: “We support clean, green energy from wind but we have to protect the national park, designated as one of the country’s most precious landscapes.

“In general we believe offshore wind farms are more acceptable than those in the countryside or near to people’s homes. You’ll be able to see these turbines from the seafront and from key viewpoints in the Downs. We certainly don’t think they’ll improve the view but we may have to live with that if they produce a significant energy output."

E.ON has already pledged to avoid environmentally and historically significant areas when laying the cable, including the route of the Adur river valley.

It said grass and hedgerows will also be replaced.

Chris Tomlinson, Rampion development manager, said it is too early to commit to major infrastructure projects.

He said: “E.ON has a strong track record with existing offshore wind farms of working with communities and supporting local initiatives and projects. However, it’s too early for us to be considering specific projects and those suggested by the South Downs Society are significant infrastructure projects in their own right and we have no authority over the pylons of other energy companies or the cement works, which is not within our cable route."