WASHINGTON - The US Department of Justice on April 30 moved to make marijuana use a less serious crime, a source familiar with the matter said.

If finalised, the policy change could potentially be the biggest shift in federal cannabis policy in 40 years.

Shares of cannabis firms surged following the news. Stocks of pot companies such as Tilray, Trulieve Cannabis and Green Thumb Industries were up more than 20 per cent in late afternoon trading.

The Department of Justice, which oversees the Drug Enforcement Administration (DEA), recommended that cannabis be classified as a so-called schedule three drug, with a moderate to low potential for physical and psychological dependence, instead of schedule one, which is reserved for drugs with a high potential for abuse.

The proposal is being sent to the White House Office of Management and Budget for review and to finalise the rule-making process, the source said.

The DEA did not immediately respond to a Reuters request for comment on the recommendation, first reported by the Associated Press.

The shift, however, would not legalise marijuana outright for recreational use, according to AP. REUTERS