The Small Business Administration has published final regulations for a new loan program for businesses that suffer "disasters" other than those caused by the weather.

The new rules permit businesses that have been hurt by a federal action to qualify for the low-interest loans. The law applies to farms that were hurt when owners lowered production as part of the Reagan administration's payment-in-kind program. But Bernard Kulik, SBA's deputy associate administrator for disaster assistance, said the regulations might be extended to cover other situations.

"Any potential disaster has to be decided upon by a state's governor and we have to agree that it is an adverse federal action," Kulik said. "Nothing, except PIK, is covered for sure."

The final rules reflect one major change that Congress ordered the SBA to make in the agency's proposed version. The SBA had specified that 25 firms in a county had to be affected before firms in that county could qualify for the aid. Now only 25 firms in a state must have been affected for a governor to seek the aid.

Since eligibility still is determined on a county-by-county basis, a governor would have to certify that a county had suffered a "substantial disadvantage" if fewer than 25 of its businesses were affected, Kulik said. "In some cases, a few major employers could be harmed in a way that results in a substantial economic injury to a county."

The rule also limits the counties that could apply for aid under the PIK program, Kulik said, to stop places "like Philadelphia, which may have one or two farms," from applying. No counties in Maryland or Virginia were included on a list of counties that the SBA already has decided are eligible.

The SBA also published revised rules for a new program in which it will provide disaster loans to businesses along the Mexican border that were hurt when the peso was devalued in 1983. Like the other rule, the final version of the border-business regulation removes a previous restriction requiring at least 25 businesses in a county to be injured before the county could qualify. The rule listed 36 counties where businesses could now qualify.

The rule refers only to "currency fluctuations" along a border, so technically business along the Canadian border could qualify if they encountered similar problems.