The proposals were put under the legal spotlight on Monday when the High Court granted an urgent hearing for a case filed by the Lewes District Friends of the Earth.

The organisation applied for the judicial review because they say the planning committee which considered the scheme ignored long term regional recycling targets.

But late yesterday afternoon the Court ruled that the planning process was sound.

The project, which is part of a joint contract between East Sussex County Council, Brighton and Hove City Council and the waste management company Veolia, has caused widespread anger among many Seaford and Newhaven residents.

Seaford MP Norman Baker has criticised the plans and more than 14,500 letters were sent to the county council listing environmental, health and social objections to the proposals when the application was first published.

And feelings were running high yesterday as protestors broke into the site of the proposed incinerator in the early hours of morning and a woman was later arrested for allegedly obstructing and assulting police.

The group locked themselves to equipment and climbed the boom of a crane. A security guard who raised the alarm was locked into the compound but released unharmed when police arrived at the scene.

And just after 4pm yesterday 11 protestors remained on the site as negotiations went on to get them to come down from the crane.

Campaigners were given some consolation last year when the incinerator's pollution permit was quashed by the High Court in a separate legal challenge and they remained hopeful that the latest hearing would rule in their favour.

Reacting to the result of the Newhaven incinerator High Court case today, Phil Michaels, Head of Legal at Friends of the Earth said, "We are disappointed the High Court did not accept that the decision to approve the Newhaven incinerator was unlawful.

"We are still very concerned that this incinerator will prevent the achievement of recycling targets.

"We will now carefully consider the Court's judgment before deciding whether there are grounds to appeal."

A spokesman for Veolia Environmental Services' who will operate the incinerator said last night, "We are pleased with the decision from the judge on this matter. We will endeavour to build this much needed facility for the communities of East Sussex and Brighton & Hove to ensure they have a place for their residual household waste to go as local landfill is running out.

"Recycling is always the first option to treating waste and the Newhaven site will only process materials that could not otherwise be recycled generating electricity for the area and diverting waste from landfill."