Uruguay's leading opposition candidate said he would try to repeal much of the country's ground-breaking marijuana law, which permits the commercial production and sale of the drug, if he wins Sunday's presidential election.

The South American country became the world's first to allow the cultivation, distribution and use of marijuana, but almost two in three Uruguayans oppose the pioneering experiment that aims to wrest control of the trade from drug gangs.

"I will keep the law's articles that allow users to grow their own cannabis at home and authorize smoking clubs and repeal the rest, in particular the state's commercialization of the drug," Luis Lacalle Pou told Reuters.

This was the first time the 41-year-old candidate for the centrist National Party has commented on the actions he would take on the marijuana law.