The increased cancer risk that comes with drinking alcohol can be offset, in part, by physical activity, new research shows.

Just two-and-a-half hours of moderate physical activity per week can cancel out the increased risk of cancer caused by drinking alcohol, an international study has found.

It is yet more evidence of the medicinal powers of regular physical activity.

Published in the British Journal of Sports Medicine, the observational study of more than 35,000 people between 1994 and 2006 found that for alcohol drinkers physical activity decreased the risks of dying from cancer.

Inactive moderate drinkers - equivalent to an average 2.4 standard drinks per day for men and 1.6 drinks for women - have a 36 per cent greater risk of death from cancer, according to the data.

For those who were physically active the association was effectively nullified, said Professor Emmanuel Stamatakis from the University of Sydney.

All it took to offset the increased cancer risk from alcohol was 150 minutes per week of moderate-intensity activity such as brisk walking.

When you break it down, this is an average 20 minutes of exercise per day.

"Our research suggests that physical activity has substantial health benefits even in the presence of potentially unhealthy behaviours such as drinking alcohol," said Prof Stamatakis.

The findings don't suggest exercise gives people a licence to drink - because alcohol abuse causes other significant health and societal issues - but they should compel and empower people to invest in physical activity, he said

Prof Stamatakis also noted that their findings refute the notion that moderate alcohol consumption is linked to health benefits.

"In this study, overall for the whole group of people we didn't find any moderate alcohol consumption benefit to health, with the exception of those only who were active," he said.

Physical activity and exercise are an extremely powerful and positive health influence and policy makers need to work much harder to come up with long-term policies to make environments more physical-activity friendly, Prof Stamatkis implored.