European Union officials have launched an inquiry into the legality of a £1 billion 25-year contract for dealing with waste.

EU environment commissioner Stavros Dimas will investigate complaints by Euro MP Caroline Lucas that the agreement between East Sussex and Brighton and Hove councils and refuse contractor Onyx was signed without sufficient public consultation.

Ms Lucas' Green Party claims the contract may be in breach of the Aarhus Convention on access to environmental decision-making.

It is unclear what censure the EU could give the councils' joint waste authority but any finding against the contract would seriously damage its credibility.

Dr Lucas said: "The Aarhus Convention gives local communities the right to participate from an early stage in environmental decision-making and I have asked the Commission to investigate whether East Sussex residents were given this right on this occasion."

Although the Onyx contract was awarded more than two years ago, it was not until last week that Brighton and Hove City Council approved the Waste Local Plan, a strategy for dealing with waste in the future.

East Sussex County Council is expected to approve the document on December 6.

Dr Lucas said: "As the integrated waste management contract was awarded before the Waste Local Plan was adopted I fear commercial considerations may have been given undue weight in influencing the plan rather than the other way round, as it should be.

"Whilst it may be too late to scrap the contract - that is a matter for the Government if the EU Commission agrees that EU law has been broken - it is certainly not too late to listen to local people's views about the way their waste is managed and incorporate them into the Waste Local Plan."

In a joint statement, East Sussex County Council and Brighton and Hove City Council said the waste contract was procured and awarded nearly two years before the Aarhus Convention came into force in the UK.

The statement continued: "We are absolutely confident that the contract procurement and award remains, and would have been at the time, fully compliant with the obligations of the Convention."

Onyx said it was committed to fulfilling its responsibilities under the terms of the waste contract.