MEXICO CITY - Mexico this week legalized possession of small quantities of drugs such as heroin, marijuana and cocaine, arguing that limited resources are better used in the fight against organized drug crime.

Individuals will not be prosecuted for possession of "any of the narcotics listed, at the listed quantity or less," reads in part the new law, published in the Official Gazette August 20.

The change means Mexicans can possess up to five grams of marijuana, 500 mg of cocaine, two grams of opium or 50 mg of heroin among other drugs without fear of prosecution.

Instead of charging people with drug possession, the new law calls on authorities to inform health providers so that rehab or other medical action can be pursued. But it was not immediately clear how that process would work.

The law, backed by President Felipe Calderon, drew considerable fire in the country's Congress in April but passed nonetheless.

Drug-related violence has spiraled nationwide since Calderon launched a military crackdown in December 2006 on the country's powerful drug gangs and organized crime, involving more than 36,000 troops.

The president argued that the country's resources would be better utilized against the drug cartels responsible for thousands of deaths throughout Mexico than in arresting drug users for possession of small quantities of narcotics.

Some US media outlets have voiced concern that the new law might encourage US drug users to engage in "drug tourism," visiting neighboring Mexico to take advantage of its new narcotics rules.