At a time when "redlining" by insurance companies has become as much a problem in some cities as mortgage redlining, the acting federal insurance administrator is trying to persuade a Senate subcommittee to recommend a one-year extension for federal crime and riot insurance programs, due to expire April 30.

Both are part of the National Insurance Development program enacted after the riots of the 1960s, when inner-city businesses were unable to get coverage from private companies. To date only 33,000 crime insurance policies have been sold. For every premium dollar the government has taken it, it has paid out $3, for a total of $20 million, acting administrator J. Robert Hunter told the Senate Subcommittee on Housing and Urban Affairs. The riot program, on the contrary, has 750,000 policies in effect and a $104 million surplus.

The reason Hunter and insurance industry want the program extended is not because they believe riots are imminent or that the property crime rate are about to soar. Their backing derives from what Hunter says is the real meaning and force of the National Insurance Development Program: the Fair Access to Insurance Requirements (FAIR) pools, which make property insurance available to inner-city residents unable to get private insurance.

More than 750,000 homes and businesses are insured in the FAIR plans of 25 states, the District and Puerto Rico.

If the program were eliminated to get rid of unprofitable crime insurance and possibly outmoded riot insurance, property coverage also would go, because many state pools are tied to federal reinsurance, the subcommittee was told. The need for this last type of insurance has increased as private companies - smarting from losses in the fields of auto, malpractice and product liability - have been reluctant to write inner-city policies, which they consider high risk.

Former Federal Insurance Administrator George K. Bernstein told the subcommittee that the existence of federal reinsurance "has encouraged insurers to be more liberal in making insurance available in urban areas."

But C. Robert Hall, vice president of the National Association of Independent Insurers, said that his group feels there is no longer a need for federal riot reinsurance or assistance in providing property insurance.

Meanwhile, a recent study by the Detroit City Council revealed that some insurers there instruct agents to write no new business in the city. Some companies deny coverage by zip code area, in effect "redlining" whole neighborhoods, the Council discovered.

According to the report, Home Insurance, Traveller's and Fireman's Fund have circulated advisories internally saying that certain zones are ineligible, subject ot caution or mandatory deuctibles. The companies list many of the same zip code numbers on these internal advisories. Most of the neighborhoods are in central Detroit.

Inspection companies, the study continued, brand some neighborhoods as "detriorating" or undesirable" and disqualify all homeowners there from insurance.

"Insurance companies capriciously decide that neighborhoods are areas of high crime and vandalism exposure" and refuse to write insurance in these nebulously defined areas," the study noted. Cancellation and non-renewals take place in areas of unfavorable loss experiences regardless of the individual claim experience - and the situation is getting worse, the study added.

Last fall a Washington-based civil rights group sued the Public Service Mutual Insurance Co. of New York because it wanted to cancel the policies on buildings in black and Puerto Rican sections of New York City. The suit was settled out of court, with the insurance firm agreeing to extend the policy until this April. As a result, the court never got a chance to rule on whether insurance redlining is covered under civil right act.

For the residents and businesses of these neighborhoods and property pool is necessary, but expensive. Only two states, Massachusetts and Rhode Island, offer comprehensive homeowners insurance under the FAIR plan.So liability, theft and vandalism coverage must be purchased separately.

Hunter's office calculated that insurance on a $30,000 frame dwelling in Washington housing one or two families, ranged from $78 to $111 a year when bought in the voluntary market. When purchased from the FAIR pool, the same coverage would cost $318. In Manhattan the voluntary market ranges from $174 to $220, while the pool insurance costs $561 a year.

James Cubie, testifying for Public Citizen Congress Watch, a Washington organization, told the subcommittee that Baltimore city residents get half the coverage but pay 50 per cent more for it. He cited the case of a couple whose premiums doubled after a move from a $36,000 house in Columbia, Md., to a $40,000 house on the fringes of the rehabilitated Bolton Hill neighborhood of Baltimore.

Those covered by the Maryland Joint Insurance Associates pool, must wait up to 90 days to get paid for a claim instead of the customary 30 days, Cubie said. They must pay by money order or certified check instead of personal check. And just getting a policy can take 90 days instead of one in the voluntary market.