The District's public service commission yesterday denied a request by Washington Gas Light Co. to raise rate on an interim basis by 6.5 million a year, pending the outcome of a larger rate case.

Washington Gas angrily denounced the regulatory agency's decision as "incredible," and said an immediate request for reconsideration will be filed.

The Washington-based natural gas utility said it currently is losing money on its D.C. business. "We have to use earnings from shareholders on Maryland and Virginia operations to subsidize service in the District," the company stated. "This is not fair."

The gas company asked the PSC to raises rates by Nov. 1, in time for the winter heating season, when it filed earlier this year for an overall $17.8 million annual rate boost. WGL's proposed $6.5 million interim increase would have been subject to refunds if the agency found later that the increase with not justified.

In its decision yesterday, the PSC said there is no justification for an emergency rate increase at this time because the company's overall financial condition faces no threat.

Said Washington Gas, in response:

"Delays by the commission in facing up to the company's financial problem in the District will only make them worse. The commission apparently ruled against (a rate hike) in the District in the mistaken belief that losses in District operations are all right as long as earnings are satisfactory in Maryland and Virginia."

Earlier this week, WGL reported a substantial decline in profitability for the 12 months ended. Sept. 30.