The Canadian government is ready to pardon those with a pot possession record of 30 grams or less as Canada became the second and largest country with a legal national marijuana marketplace on Wednesday.

A senior government official said those with a record will be allowed to apply for a pardon. The official was not authorised to speak publicly ahead of Wednesday's announcement and spoke on condition of anonymity.

On Wednesday, Canada became the second country after Uruguay to legalise so-called recreational marijuana. Tom Clarke, 43, shop opened at midnight in Newfoundland, Canada's easternmost province.

"I am living my dream. Teenage Tom Clarke is loving what I am doing with my life right now," he said.

Clarke has been dealing marijuana illegally in Canada for 30 years. He wrote in his high school yearbook that his dream was to open a cafe in Amsterdam, the Dutch city where people have legally smoked weed in coffee shops since the 1970s.