Mexico's president will approve a law that decriminalizes possession of small amounts of marijuana, cocaine and other drugs to concentrate on fighting violent narco gangs, the government said on Tuesday.

Under the law, police will not penalize people for possessing up to 5 grams of marijuana, 5 grams of opium, 25 milligrams of heroin. Nor does the law penalize possession of 500 milligrams of cocaine -- enough for a few lines.

The legal changes will also decriminalize the possession of limited quantities of LSD, hallucinogenic mushrooms, amphetamines, ecstasy and peyote -- a psychotropic cactus found in Mexico's northern deserts.