A leading scientist has called for an inquiry into emissions from an oil refinery and a power plant, claiming they could be responsible for cancer, heart attacks and strokes among thousands of Scots.

Dick van Steenis said he has pinpointed a corridor of sickness between the giant BP Amoco refinery at Grangemouth and the Kilroot power station in Ulster.

Following his own investigations, he believes the effect of pollution from the two plants could be "devastating" within a 44-mile radius.

Representatives for both plants say they have a clean track record when it comes to pollution and comply with legislation on emissions.

Dr van Steenis, who has advised the House of Lords select committee on pollution, said he had mapped the pattern of emissions from the two plants which, he said, carry dangerous chemical particles across a wide area.

"If you look at a map of the patterns followed by plumes from these places it becomes abundantly clear that there's a problem," he said.

"The two plants could be responsible for the bulk of cancer cases in the areas they pollute. Cancer patterns can be di rectly linked to these plants and the line you can draw between them.

"Where the pollution grounds you are always going to have death and illness and in this case that means most of central Scotland."

Dr van Steenis said poor diet and lifestyle were not enough to account for Scotland's appalling record of ill health and the plant emissions might explain health anomalies like a higher than normal incidence of prostate cancer in East Lothian and Glasgow's poor mortality rate.

A spokesman for BP Grangemouth said the company had an open dialogue on issues such as pollution and a clean track record. He said a 10-year air monitoring programme had found nothing dangerous, and the plumes emitting from the refinery were water vapour.

A spokesman for Applied Electricity Services, which runs the Kilroot plant, said: "For environmental emissions from the plant, we have to comply with legislative limits. The plant operates well within these limits and our performance record is readily available in the public domain."

A Scottish executive spokesman said it would study Dr van Steenis's concerns carefully.