The General Accounting Office declared yesterday that the District of Columbia's police and firefighter retirement system is so generous and costly that 1,500 federal employees now covered by the city plan should be pulled out.

Although the city requiries smaller retirement contributions from its employees than does the federal civil service system, the GAO found that the District offers earlier and more generous retirement and death benefits than the federal system. The city also allows retirees to collect higher pension benefits while holding down post-retirement jobs.

The 1,500 federal employees now covered by the city's retirement system are members of the U.S. Park Police and the Secret Service. Because of special congressional actions, officers in these agencies have traditionally been covered by the D.C. retirement plan and also received pay increases equal to those given city policemen.

The result GAO said yesterday, is that "they receive higher pay for the same levels of work and have much better retirement benefits than their federal civil service counterparts," including members of the U.S. Capitol Police and Library of Congress guards.

The GAO said it would be best to sever the long-standing interrelationships of pay scales and pensions of the city and federal police. Such a separation would allow both governments to better plan, control and administer their respective retirement systems, the GAO concluded.

Although much of the GAO report focused on the police and fire retirement system, the agency also recommendement that the city and the federal government each run its own pay and retirement systems.

This recommendation would affect all 47,000 city employees, many of whom are currently covered by federal pay and wage scales and U.S. civil service retirement and benefit programs. City police and firemen have a separate retirement plan.

The City Council is already preparing legislation, expected to take effect next year, that would establish a separate city civil service system.However, yesterday's GAO recommendation urged the city to go one step further and set up its own retirement system as well.

The GAO argued in making its recommendations that a separate retirement system run by the city government - D.C. and federal retirement provisions are currently interchangeable in many cases - would be a logical outgrowth of the limited home rule granted the city in 1975.

However, Mayor Walter E. Washington, in a letter accompanying the 31-page report, flatly opposed the city having its own retirement system and pension payment bill.

The mayor said he was concerned that the creation of two separate systems would be detrimental and unfair to the many city workers who have been working on the assumption of being simultaneously in the federal and city plans.

Equally important, the mayor said, were the "financial implications" of an independent city system - an apparent reference to the fact that because the home rule government has in herited a costly and antiquated pension system, it would be strapped with enormous financial burdens if it were to assume the huge annual pension bill, the payment of which is now shared by the federal government.

In the fiscal year that ended last September, nearly one-third of the entire D.C. Police and Fire Department budgets - $55 million - was used to cover pension benefits under the city's costly "pay as you go" system.

Last month, D.C. Police Chief Maurice J. Cullinance announced that he planned to retire on disability because of a knee injury suffered during a 1968 demonstration. The city's police retirement board said Cullinance was eligible for $31,000 a year in tax-free disability retirement payments.

The police chief is expected to retire this week, and join the ranks of 83 per cent of the city's 2,200 retired policemen who receive the tax-free disability payments. Some city finance officials believe the police retirement system - with its overwhelmingly disproportionate number of disabled retirees - has gotten out of control.

The special status of the three police agencies for when the 1,500 federal employees work stems from the fact that many years ago these agencies either assumed duties formerly done by the D.C. Police Department or were largely formed of men who transferred from the city's police force.

Because city police wage increases since 1958 have been greater than those for other civil service employees, these men now make more money than their federal counterparts, the report said. For example, a park police officer earns $13,799 a year while an equivalent civil service worker earns only $9.959 or 39 per cent less, the report said.

A major benefit the 1,500 gain from the retirement system after leaving the force is that they can receive full pay while working on a federal job and still collect fell pension benefits. Retired federal civil servants are required to have their salary reduced by the amount of money they receive in retirement benefits if they take a post-retirement job with the U.S. government.

The GAO said that because of legislation passed since 1970, the District's police and fire retirement system is "one of the most liberal systems in the country."

When the D.C. system was compared recently to the retirement benefit packages offered by eight other major American cities by Syracuse University researchers, the GAO said, "the benefits provided to District police and firemen were in most respects the best."