Uruguay is to limit marijuana sales to 10 grams a week for each licensed user when it publishes the rules for its legal market.

The full set of rules are already two weeks overdue.

Uruguay's president, José Mujica, had asked that no details be released until the regulations were finally published on Friday or Monday, but an official in the drug control office, speaking on condition of anonymity, said the 10g weekly limit was intended to thwart illegal resales.

Pharmacies would also not be permitted to sell the 40g monthly allocation all at once.

The delay in publishing the full set of rules was blamed on the law creating Uruguay's legal marijuana market not including measures on taxing sales, so authorities are developing fees to match highly taxed alcohol and cigarette sales.

Another problem was figuring out how to trace the plants from seed to smoke.