In an agreement with the Washington chapter of the NAACP yesterday, the Washington Gas Light Co. pledged to double the amount of goods and services it buys from Washington area minority contractors, to at least 25 percent.

Richard Vierbuchen, WGL executive vice president, said the agreement was expected to generate an estimated $10 million worth of business for minority-owned companies, which currently provide 12 1/2 percent of all the goods and services that the utility buys from local suppliers.

The agreement signed yesterday is in large part a restatement of a "Declaration of Fair-Share Principles" that the national NAACP signed last year with the American Gas Association, of which Washington Gas is a member.

"The NAACP last year had conceived the idea of trying to increase opportunities for blacks to sell goods and services to corporations throughout the country," said John Harvey, a representative of the NAACP.

"And it seemed that the gas companies were a good starting point. After all, they're something that we all have to use, so it's only fair that a proportionate share of the business opportunities it provides go to the black community."

At a press conference in the utility's offices on 11th and H streets, Edward Hailes, president of the Washington branch of the NAACP, read from the "Declaration of Fair-Share Principles" in which the company promises to review opportunities available to black-owned businesses and black professionals, to consider additional blacks for membership on the board of directors, and to review the appointment of blacks to senior management positions.

"Like many other corporations, we're striving to cut down on inventory," Vierbuchen said. "but we estimate that our total purchases from local providers of goods and services will amount to $40 million this year."

As part of the agreement, Vierbuchen said, Washington gas made a commitment to provide assistance for minority businesses in developing their competitive status.

Asked what kind of leverage the NAACP had used in persuading the gas company to draw up the joint statement, Hailes said the organization relied on "the company's willingness to do the job that has to be done, on its moral dedication."

Listening in, Donald J. Heim, president and chairman of the utility, said that although goodness had something to do with it, "the basic principle is that services and goods are available from minority vendors at competitive prices. It's sound business to support the community you work and live in."