Recreational pot use was barely legal for 24 hours in Canada before RCMP in Manitoba made their first arrest of a driver they say was impaired by the drug.

Mounties patrolling a checkstop at Cree Road and Deerwood Drive in the northern Manitoba city of Thompson say they became suspicious when they noticed a SUV turn away from them around 12:55 a.m. on Thursday.

An officer pursued the vehicle, stopped it and noticed the odour of cannabis and signs of impairment from the driver, RCMP said.

The 20-year-old man from Thompson admitted to recently smoking cannabis, police said.

He was given a standardized field sobriety test, conducted by a police officer, which determined the driver was impaired, RCMP said. He was arrested for impaired operation of a motor vehicle and taken to a nearby medical facility, where his blood was tested.

The man's driver's licence has been suspended, but police cannot lay charges until results of the blood test are received.

He is believed to be the first person arrested by Manitoba RCMP for driving under the influence of cannabis since use of the drug was legalized on Wednesday, spokesperson Tara Seel said.

There is no legal cannabis retailer open in Thompson at this point. The closest legal pot shop is in Dauphin, more than 500 kilometres away.