Wal-Mart Stores Inc is still learning about the Russian market, a country it sees as underserved by retailers, a top Walmart International officer said on Thursday.

Walmart has a growing presence of employees, but no stores, in Russia as it tries to understand what it takes to succeed in that market, Cathy Smith, Walmart International' chief financial officer, said.

In May, sources said that Wal-Mart was in preliminary talks to acquire Russian retailer Lenta after years of trying to enter that market.

Smith did not comment on particular acquisition targets, but said the company tends to prefer to make an acquisition to enter a country in order to have the size to operate the Walmart model of saving costs through scale and productivity that lets the company offer low prices.

Walmart is also looking to increase sales in markets where it already is, including China, Chile and Brazil.

Walmart's international sales, at over $100 billion, accounted for about a quarter of the company's sales last year. But the company does not have a target for how much those sales will make up of the total going forward.

(Reporting by Brad Dorfman, editing by Dave Zimmerman)