NO nuclear, biological or foreign waste will be deposited if 1,000ft-deep salt caves are used as a giant dump, protestors were assured yesterday.

But the US company behind the plan to pump "hazardous waste" into caverns near Hartlepool could not say exactly what would be dumped.

Protestors said they will continue to fight the plans by US-owned company Coastal Caverns UK to dump what would be largely chemical waste.

Louis Ross, director of the Texas parent company of Coastal Caverns, came to Teesside to try to reassure the public that the proposed £4m operation would be safe if planners at Hartlepool Borough Council and the Environment Agency give planning permission.

The scheme, for 16 brine caverns under land between Greatham Creek and Huntsman's Tioxide plant, near Seaton Carew, would create 15 jobs.

Much of the waste, which would be likely to include metal, slurry, slag and ash, would come from Teesside's chemical plants. The dumping ground would cover a 25-acre site. The waste would be pumped down 10in to 12in wide shafts, and displaced water would be pumped out.

Mr Ross said there would be no stockpiling of waste on the ground.

He conceded that the waste would be hazardous as defined by the Environment Agency and would not be degradable.

But he said: "I would certainly be prepared to live in the area. This is very safe."

Geoff Lilley, ward councillor for Greatham, and Hartlepool resident Peter West have pledged to continue to oppose the plan, which could start operating by the end of next year.

Mr West, who has a biochemistry degree, said giving planning permission would set a precedent and allow other hazardous waste to be dumped on Teesside. He said that even a minor leakage would pollute nature and scientific sites.

Councillor Lilley said that everyone he had spoken to opposed the plan and feared it could have a devastating environmental impact.

It is expected that Coastal Caverns UK will make an application for planning permission in the coming months.