Because of an editing error, a reference to the SM2 nuclear warhead for an antiaircraft missile was dropped from a story yesterday about the Anti-Submarine Warfare Standoff Weapon. The SM2, rather than the submarine weapon, has been designed to carry a neutron warhead. The administration is seeking production funds for both.

The Reagan administration is asking Congress for money to prepare for production of a new nuclear antisubmarine weapon that the chief of naval operations acknowledges would black out U.S. as well as Soviet listening devices on nearby ships and submarines if it were used.

The Anti-Submarine Warfare Standoff Weapon (ASWSOW), which could cost up to $2 billion or more to complete and would replace a 20-year-old system, is among several unpublicized nuclear systems that the administration wants to build.

Adm. James D. Watkins told a Senate Armed Services subcommittee in February 1985 that after an ASWSOW explosion, the "insonification of the water for a period of time would rule out sensors for anybody in the immediate vicinity."

He added, however, that the blackout would fade "in hours . . . and the kinds of warfare we are talking about deal in hours, except in the most extreme cases."

"It disappears," Watkins said, "and our systems are sensitive enough within a short period of time to be picking up the kinds of information we need to continue progressing the conflict."

At the same hearing, Navy Secretary John F. Lehman Jr. responded to questioning from Sen. Edward M. Kennedy (D-Mass.) by saying that the weapon would be used "only in retaliation for their being used against U.S. submarines."

Asked by Kennedy if he was "suggesting 'no first use' of these tactical weapons," Lehman replied, "I would not make any declaratory policy. I would just say that it is de facto tactical common sense not to use them first in naval warfare."

ASWSOW is being built, Lehman said, "to deter the Soviets from gaining any advantage by going nuclear at sea."

"We think that . . . the maintenance of a balance in that area prevents a temptation to use them in the future."

The Department of Energy is seeking $47 million in fiscal 1987 -- and eventually $126 million -- to prepare facilities for production of ASWSOW. A congressional source described it as the "biggest new start" next year for nuclear weapons.

ASWSOW, developed by the Boeing Co., is both a missile and a depth bomb. It is to be launched from surface ships or underwater from a submarine, rocket upward through the air, aim and then drop like a bomb, exploding at the correct depth to destroy the enemy boat.

Development costs were projected at $500 million in 1980, with production of 1,000 missiles put at more than $2 billion by the General Accounting Office in 1982.

In the past, Congress has turned down funds for a nuclear version of ASWSOW, citing the damage it would do to U.S. radars in the area of an ASWSOW explosion. Congress also objected to the Navy's inability to explain how it would get presidential release to use the nuclear weapon in time against enemy craft.

Last summer, to meet congressional objections, the Navy agreed to put a neutron warhead on the system so that its explosion would affect a smaller area. Neutron weapons are nuclear devices that produce larger amounts of radiation energy but less heat and blast than traditional nuclear systems.

In a related matter, sources said the next U.S. underground nuclear test, code-named "Mighty Oak," would be ready for firing Tuesday, but could be delayed "a day or two" depending on weather and other factors.

The low-yield nuclear effects test will be used in part for a Strategic Defense Initiative experiment to determine the lethality of X-rays produced by the blast. Its radiation will also be used to see whether the protective covering on warheads for the new MX land-based intercontinental missile and the Trident II sub-launched missile can be penetrated.