Raleigh Stores Corp., the largest independent clothing stores chain in the metropolitan area, yesterday was struck for the first time since its employees were organized 40 years ago.

The strike by the United Food and Commercial Workers, Local 400, came just one day after efforts by a federal mediator to break deadlocked negotiations came to a halt.

The union contract, which expired on March 28, covers 565 Raleigh employees at the chain's 11 stores.

Among the issues in the negotiations are the complex wage formulas under which salespersons in the men's and women's clothing and furnishing stores are paid.

Raleigh's officals say they have proposed an increase in the basic commission rate for their salespeople, raising the percentage of sales figure from 7 5/8 percent to 8 percent.

But Tom McNutt, president of Local 400, says the store is granting the increase, while at the same time cutting the size of the work force in order to do so.

"If they raise the price of the merchandise, just by inflation, they'll make that 8 percent," McNutt said.

On the other hand, Raleigh's officials say the average income for their salespersons is $22,820 and cite their labor relations record, a jointly managed health plan, and other benefits as evidence of their efforts.

A second major issue in the strike revolves around Sunday work, Union officials say the company proposal would remove seniority as a factor in setting Sunday schedules. On Sunday, Raleigh's workers are paid one-and-a-half times average daily earnings.

Raleigh's officials said yesterday the strike hit them by surprise.They said they offered concessions to the union in the past that put them in a financial and bargaining hole.

"In our previous settlements, we allowed ourselves to be pushed further than we should have," said Brainard L. Janicki, the chain's executive president.

McNutt argues that Raleigh's has not upped its pension benefits in the last four contracts, which covers the years since 1972.

"I'm ready to bargain," McNutt said. "I would sell an 8 percent increase to our members if it were such."

McNutt's union has become increasingly visible in the retail business of late and the Raleigh's strike indicates the unions's activities. Last year, the union organized a large contingent of employes at Woodward & Lothrop in a major membership push.

Raleigh's officials, however, say they are being "singled out," in this strike as a way for the union to demonstrate its willingness to strike. McNutt denies the charge.

All 11 Raleigh's stores were picketed yesterday but Raleigh's officials emphasized that they were able to use management people, their relatives and friends of the store" to continue operations.

One union official said "we have almost shut the operation down." Raleigh's officials said they will continue normal hours for the duration of the strike.