The D.C. police department, under pressure to cut costs by not granting holiday pay, has reduced the number of policemen working by as much as 72 percent on some holidays, D.C. Auditor Matthews S. Watson reported yesterday.

Watson said on two such holidays -- Columbus Day and Martin Luther King's birthday -- the number of crimes and calls for police assistance were no less frequent than on ordinary days. But the number of police was down from the usual 1,728 to 490 on King's birthday and 584 on Columbus Day because both are recognized as official holidays by the city.

"You're taking a risk that something will happen on these two days," Watson said, "and we won't have enough police officers."

The police department routinely reduces the size of its force for Thanksgiving, Christmas and New Year's Day, since most businesses are closed and there is not as much traffic in the city. Police officers who work those days receive double their usual wages.

But according to Watson's report, on Columbus Day most retail businesses remain open, and on Martin Luther King's birthday, a local holiday, federal employes all report to work.

Maurice Turner, assistant chief for field operations, said he has not yet seen the report. But, he said, staff reductions have long been common on holidays, and the austere budget conditions the city now faces may have increased the number.

"I don't see any noticeable increase in crime during those holidays," Turner said, declining to make any further comment until he has read the report.

There was no reduction in crimes, according to the report," and the frequency of some crimes actually increased on the holidays when the force had been drastically reduced.

For example, on King's birthday Jan. 15 there were 20 robberies, 34 burglaries, 88 larcenies, 11 automobile thefts, and a woman was raped.

On Feb. 12, a date chosen for comparison, there were 13 robberies, 33 burglaries 66 larcenies, only three cars were reported stolen and no women said they were raped.

Watson said that the premise underlying his report is "there's a lot of data in this city that should be used for planning purposes" instead of for financial purposes and balancing the books.

Watson said police department officials could have easily collected the same data in his report, and drawn the same conclusions if they were more interested in long-term planning and somewhat less cost-conscious.

"it appears that police manpower management is a financial, rather than a planning effort," Watson said. "they're only looking at the money" and not at the effects of the severe police manpower reduction on crime prevention, he said.

The auditor's office is the local equivalent of the federal General Accounting Office, preparing independent studies and acting as a sort of inhouse watchdog over the city's fiscal efficeincy and management.