Walmart, the largest retailer in the United States, cancelled a plan to open its first discount store in Manhattan due to strong opposition from labor unions, local media reported on Wednesday.

H. Lee Scott Jr., Walmart's chief executive, told The New York Times on Tuesday that conducting business in New York is so expensive and exasperating that "I don't think it's worth the effort."

Walmart spokeswoman Mona Williams, however, clarified afterwards that Mr. Scott was referring to Manhattan only, not the entire city.

The company has been trying to crack into urban markets and expand beyond its suburban base throughout most of the country, but has encountered stout resistance to its plan to enter America's bigger cities, such as New York, Chicago, Cleveland, and Los Angeles.

Fearing that the retailer's low prices and modest wages will undercut unionized stores, labor unions have built anti-Walmart alliances with Democratic members of city councils.

Walmart, which has nearly 4,000 stores in the U.S., has failed to open stores in Rego Park, Queens, and in Staten Island in the face of intense union, community and political opposition.

According to latest surveys, Walmart's grocery prices are typically 10 to 30 percent lower than those of its competitors. But labor leaders asserted that while Walmart's prices are low, its wages and health benefits are so skimpy that they may leave many workers below the poverty line.