A renowned British scientist who established that smoking causes lung cancer was on the payroll of a chemical company while investigating cancer risks, it was reported last night.

Sir Richard Doll, who died last year aged 92, was said to have received a consultancy fee of $1,500 a day during the mid 1980s from the chemicals firm Monsanto, which is now associated with GM crops.

Doll, an epidemiologist, also received payments from the Chemical Manufacturers Association and the companies Dow Chemicals and ICI, The Guardian reported. It said the three organisations paid him £15,000 to assess the potential dangers of vinyl chloride, used in plastics.

Doll largely cleared the chemical industry of having links with cancer, a conclusion which goes against the World Health Organisation's assessment. The association is said to have used the review to defend its members' use of vinyl chloride.

While on Monsanto's payroll, it is claimed Doll wrote to a government-appointed commission in Australia investigating the potential for Agent Orange to cause cancer. He said there was no evidence the agent, manufactured by Monsanto and used during the Vietnam war, caused cancer.

Doll pioneered the argument that cancer is caused by smoking, a view contested by environmentalists who point to the dangers of pollution.

His work was funded by Cancer Research UK. Its medical director, Professor John Toy, said that Doll had been working in a different era when it was "not automatic for potential conflicts of interest to be declared in scientific papers."