Up to 60 tonnes of sewage sludge is being driven across the county border every day and treated illegally in West Sussex.

Southern Water has been summoned before West Sussex County Council after inspectors investigating a stench at the Ford Sewage Works discovered the utility firm was driving four lorry-loads of sludge daily in sealed skips from Newhaven.

The complex, near Arundel, does not have planning permission to treat any sewage from East Sussex.

The council made a public announcement following the discovery at Southern Water, which is already dealing with complaints from nearby residents about an unpleasant smell caused by an unrelated systems failure.

Stephen Haymes, vice-chairman of Yapton Parish Council, said last night: "We are concerned by all traffic movement in and around Ford but this is of particular concern, especially at the moment.

"Because there is a smell emanating from the building, it is unpleasant anyway."

Tex Pemberton, the council's cabinet member for strategic environmental services, said: "The breach of the planning condition was established during visits to the sewage works by enforcement officers from the county council, who are working with environmental health officers from Arun District Council as part of an investigation into complaints about odours from the plant.

"West Sussex County Council recently doubled the size of its enforcement team from two to four as part of a drive to ensure that planning conditions attached to waste and minerals sites are being complied with."

Southern Water will explain its reasons for the breach at a public meeting and plead to the council's planning committee to be allowed to continue shipping sludge into West Sussex.

Colonel Pemberton added: "It will be for the planning committee to decide on Southern Water's proposal.

"However, I hope this does show local residents that we are vigilant and monitor sites effectively."

The Ford Sewage Works deals with waste water from the Bognor and Littlehampton area, making it clean enough to safely release into the sea.

It also treats sewage sludge - solid waste removed during the treatment process - from various works across West Sussex, recycling it into agricultural fertiliser pellets.

The company says the sludge would have been treated at a wastewater treatment works and sludge recycling centre for the Brighton and Hove area but plans to expand the works were dismissed after a public inquiry.

Bosses at Southern Water say their Ford plant already has a recycling centre to process sludge into organic fertiliser granules, which is more environmentally friendly than dumping it in landfill sites.

The company's wastewater manager, Nev James, said: "The works at Ford is a key part of our wastewater treatment and sludge recycling operations in Sussex.

"We are keen to ensure that it continues to do a vital job in safely recycling waste in an environmentally friendly way while having as little impact as possible on its surrounding area.

"We have taken the step of processing the sludge at Ford because this is the best option for the environment."