"As has been well documented, I smoked pot as a kid, and I view it as a bad habit and a vice, not very different from the cigarettes that I smoked as a young person up through a big chunk of my adult life," he is quoted as saying in a New Yorker magazine article. "I don't think it is more dangerous than alcohol."
The president said he has told his daughters smoking marijuana is "a bad idea, a waste of time, not very healthy".
However, he said he is concerned that marijuana-related arrests fall far more heavily on minorities than on others. Legalisation of pot should go forward in the states of Colorado and Washington because "it's important for society not to have a situation in which a large portion of people have at one time or another broken the law and only a select few get punished," he said.Remains illegal under federal law
Marijuana remains illegal in the United States under federal law, but 21 US states allow or are about to allow medical marijuana use, and Colorado and Washington have decriminalised use of pot entirely. Alaska and the District of Columbia are considering following suit.
The Obama administration said last year that federal law enforcement will not target users in Colorado and Washington, as long as they comply with their respective states' laws.
The Department of Justice says it will not interfere with states' efforts to regulate and tax marijuana provided they are able to meet a set of requirements, including keeping it from children and restricting its flow into other states.
'Overstating the case'
The president also said he believes that those who argue that legalising marijuana will solve a number of social problems "are probably overstating the case". Legalisation in Colorado and Washington will likely be a challenge, he said.