Consumer advocate Ralph Nader yesterday accused the Postal Service of distributing 176 million ads for four classic movies.

What provoked Nader's anger were four commemorative stamps that the Postal Service released earlier this year in honor of the 1939 movies "Gone with the Wind," "The Wizard of Oz," "Stagecoach" and "Beau Geste."

"There's more to this than meets the eye," said Nader, a former stamp collector. He described the multicolor, 25-cent stamps featuring Clark Gable, Vivien Leigh, Gary Cooper, John Wayne and Judy Garland as examples of "creeping commercialism" that are pushing postal rates upward.

In a letter to Postmaster General Anthony M. Frank, Nader charged that since the 51-year-old films remain in commercial distribution, the stamps violate the Postal Service's guidelines prohibiting stamps for "commercial enterprises or specific products."

Frank Thomas, a Postal Service spokesman, rejected Nader's complaint. "I can't imagine they need a stamp to promote these films," said Thomas. "They were just an honoring of something that was felt to be culturally important."

Echoing a complaint of many stamp collectors, Nader said the stamps illustrate how the Postal Service has become consumed by ways to merchandise its new stamps. It sells them on T-shirts, key chains, pens and other items, Nader said.

"They are not focusing on service. Try to mail a letter on the weekend. Their Express Mail is a farce and there are fewer deliveries," Nader said. "Their idea of innovation is in the direction of becoming a knick-knack store."

The U.S. Postal Service was not the only target of Nader's ire. He also fired off a complaint to postal authorities in Canada over a recent stamp issue there that carried the golden arches logo of the McDonald's restaurant chain on the borders of stamp sheets. The stamps, which McDonald's was distributing to youngsters as a promotion, not only represent unnecessary commercialism, but they also will "encourage bad diets," Nader said.