Uruguayan chemists on Thursday criticized the government's plan to allow the sale of marijuana for recreational use in the country's pharmacies.

In an announcement last week, the government said cannabis will go on sale in pharmacies within eight months, following the granting of licenses to two companies to grow cannabis for commercial sale, in accordance with a 2013 law.

But pharmacies must "work for the health of the population," and "the use of psychoactive substances for recreational use, whether legal or not, is detrimental to health," the Chemistry and Pharmacy Association of Uruguay (AQFU) argued in a statement.

The newspaper El Pais said 120 pharmacies in the capital Montevideo are interested in selling marijuana.

But AQFU said pharmacies "do not sell other recreational substances like tobacco or alcohol" and called the policy contradictory to the tobacco and alcohol policies of President Tabare Vazquez's government.

The trade group demanded a review of the cannabis law, which is the first of its kind in the world and has sparked international media attention.

Uruguayans wishing to buy cannabis in pharmacies must register in a national database and will receive a card enabling them to purchase up to 40 grams per month, which they would be forbidden to resell.

The other initiatives in the 2013 law, allowing limited growth of cannabis plants for private use and of more as part of a "grow club" have already been implemented, and proponents see the implementation of the commercial sale provisions as overdue.