UPDATE 1-Mexico court rules against Walmex worker vouchers

(Adds court ruling details, Walmex reaction)

MEXICO CITY, Sept 5 (Reuters) - Mexico's Supreme Court ruled that the country's top retailer, Wal-Mart de Mexico, violated the constitution by paying a worker in part with store cards only usable in the chain's outlets, the court said on Friday.

Wal-Mart de Mexico (WALMEXV.MX: Quote, Profile, Research), also known as Walmex and a unit of U.S. retail giant Wal-Mart Stores Inc (WMT.N: Quote, Profile, Research), gives electronic store cards as part of salaries, which the court said harked back to exploitative wage practices of over a century ago.

For now, the ruling only applies to the one worker and will not oblige Walmex to scrap the card scheme.

But if enough other employees group together to bring a similar case to court it could ensure all future rulings on the card scheme would go the same way, a court spokesman said.

During the long dictatorship of President Porfirio Diaz, which ended in 1911, wealthy landowners and businessmen paid employees with special currency only valid in company stores.

The stores, which sold goods to poor workers at inflated prices, were banned in the constitution after labor uprisings sparked the Mexican Revolution in 1910.

"A labor contract that requires workers directly or indirectly to buy items in certain stores violates the constitution and will be declared null and void," the court said in a statement.

A Walmex employee brought the complaint to the court about giving workers store cards as part of their pay.