Almost 100 gardens in Seaton Carew near Hartlepool, were found to have high levels of arsenic, lead and zinc.

Hartlepool Borough Council says the entire clean-up operation could cost as much as �4m.

It has pledged to carry out the work, despite having an appeal for cash help turned down by government officials.

Pit props

The authority is taking legal action against firms it feels are responsible for the contamination.

Experts believe the contamination stems from the storage of treated pit props on land subsequently used for housing.

The council's director of neighbourhood services, Ian Parker, said: "The council has all along committed itself to getting this process done as quickly as possible so the residents' problems of living in this contaminated area are sorted out quickly.

"The council is fully committed to seeing this happen, so the residents need have no worries that this will delay the process in any way."