An exhaustive investigation into the incidence of childhood cancer in Britain over a period of 35 years has failed to find any increased risk of leukaemia among children living near nuclear power stations.

The independent committee of scientists that carried out the study investigated 13 nuclear power plants across Britain and failed to find one that has a statistically significant "cluster" of childhood cancers among families living near by.

The findings will almost certainly be used by the Government to support its case for building a new set of nuclear power stations to meet UK energy demands over the coming decades, which many environmentalists have opposed on health grounds as well as risks to the environment.

Scientists appointed by the Government to review the evidence of a link between radioactive emissions from nuclear power stations and childhood leukaemia said the risk is "extremely small, if not zero" and that in future it would be more profitable to investigate other potential causes of the cancer, such as viral infections, rather than radiation.

Professor Alex Elliott, chairman of the Committee on Medical Aspects of Radiation and the Environment (Comare), and a distinguished medical physicist at Glasgow University, said that the estimated extra radiation dose from a nearby nuclear power plant amounts to just 0.0065 per cent of the dose typically received from natural and medical causes combined.

"While we need to keep a watching brief on radiation as a possible cause of leukaemia," Professor Elliott said, "we should be looking at other places for the cause of childhood cancers, such as viruses and other infections introduced into relatively isolated communities by outsiders – a theory known as population mixing."

Childhood leukaemia is a rare disease, affecting about 500 children each year in the UK. The scientists found just 20 cases between 1969 and 2004 among children living within 5km of a nuclear power plant, and 430 cases of the disease in children living within 25km.

None of them fell into recognised "clusters" – defined as a significantly higher number of cases in a designated area compared with the national average. There was no increased risk of childhood leukaemia associated with living near a nuclear power plant.

"Comare's primary analysis of the latest British data has revealed no significant evidence of an association between risk of childhood leukaemia in under-fives and living in proximity to a nuclear power plant," Professor Elliott said.

But previous investigations by Comare have established that there are two childhood cancer clusters near to the nuclear reprocessing plants at Sellafield in Cumbria and Dounreay in northern Scotland. The latest Comare report did not investigate these clusters but previous reports said radiation emissions from the two plants are too small to account for the excess cancers.

A German study has established a higher risk of childhood cancer around nuclear power plants, specifically a cluster around the Krummel plant near Hamburg. But Professor Elliott said that the numbers involved are so small that there might be another explanation or interpretation.

"It is extremely difficult to do these epidemiological studies and one single piece of data should not be taken out of context," he said.

To test their statistics, Comare examined childhood cancers around sites where nuclear power stations were planned, but never built. They found a statistical cluster around one site with no nearby nuclear reactor.