It follows last summer's government announcement of an inquiry into the long-term health effects of the incident at Camelford, north Cornwall, in 1988.

A contractor's relief driver poured 20 tons of aluminium sulphate into the wrong tank at Lowermoor treatment plant.

Supplies to 20,000 customers of South West Water Authority were polluted and hundreds of people drank the contaminated water without knowing.

'Crucial significance'

On Monday, the area's Liberal Democrat MP, Paul Tyler, urged parents who may concerned to contact the official investigation team which will be visiting the area on Friday.

Mr Tyler, who campaigned for an official investigation, said: "Any abnormal symptoms among those who were very young at the time - or even unborn babies - may be of crucial significance in establishing the impact of the aluminium, or the resultant cocktail of other metal pollutants in the water supply."

He said aluminium could cause short-term medical problems, and there had been claims of long-term neurological effect.

"We need to know if the cover-up after the original 1988 incident led to undiagnosed or possible mental defects," Mr Tyler added.

"Even behavioural problems may be relevant."

'Unforeseen consequences'

The government's Lowermoor Incident Health Advisory Group reported in 1989 and 1991 that there was no convincing evidence of a harmful build-up of aluminium.

It said there was no increase in ill health from poisoned water, but recognised the affair had caused "real suffering" in the community.

In 1991 it concluded there could be "unforeseen late consequences".

But a 1999 report in the British Medical Journal said people had suffered "considerable damage" to their brain function.

After a 17-day trial at Exeter Crown Court in 1991, the then South West Water Authority was fined £10,000 and ordered to pay £25,000 costs, after being convicted of causing a public nuisance by supplying water which contained amounts of the chemical likely to endanger public health or comfort.

Five years ago, 148 victims accepted out-of-court damages totalling almost £400,000, approved by a High Court judge sitting in Truro.

The settlements ranged from nearly £700 to £10,000.