Military police in Afghanistan are investigating unsubstantiated allegations that British and Canadian soldiers may have smuggled heroin out of the war-torn country.

According to a report published in British newspaper The Sunday Times, troops at the British base in Helmand province and the Canadian base at Kandahar Airfield may have been involved in trafficking the drug.

"We are aware of these allegations. Although they are unsubstantiated, we take any such reports very seriously," a British Ministry of Defence spokesperson told the newspaper.

In Ottawa, a National Defence spokesperson told CTV News the department is looking into the allegations.

Helmand province is one of the world's leading sources of opium which can be refined into heroin. Sales of the poppy derivatives generates millions of dollars each year, much of which goes to finance the Taliban.