An incorrect statement appeared in Sunday's Washington Post regarding the strategic arms limitation agreement now being negotiated between the United States and the Soviet Union. The accord would limit both sides to about 1,200 land-and submarine based missile launchers with multiple warheads. It would set a limit of 1,320 on all weapons with multiple warheads. That would allow the United States to deploy - without counting them against the 1,200 figure - up to 120 bombers armed with America's newest weapon, air-lauched cruise missiles, a system the Soviet Union is not expected to deploy during the course of the agreement.

The Carter administration, which has been under severe attack from congressional and other critics over its efforts to reach a strategic arms agreement with the Soviet Union, has launched a defensive salvo of its own.

In comments embargoed for release until today, Defense Department officials insisted that a treaty, as it is now being negotiated, would allow the United States to retain a roughly equal position in the nuclear weapons balance with the Soviets.

They conceded, as they have in the past, that U.S. Minuteman intercontinental missiles would be vulnerable to a Soviet nuclear first strike sometime before 1985, but they made these additional points:

The Minutemen would be vulnerable regardless of whether a treaty results from the current strategic arms limitation talks (SALT).

The survival of the United States does not depend on the survivability of the Minutemen. The U.S. arsenal would still have sea-launched intercontinental missiles and by 1980 would have cruise missiles, which are pilotless aircraft designed to fly low enough to evade radar detection.

Responding to criticisms chiefly from Sen. Henry M. Jackson and former Deputy Secretary of Defense Paul H. Nitze that U.S. negotiators are making too many concessions to the Soviets, one Pentagon official listed what he said were concessions by the Soviets:

They have agreed to limit the number of their land-based missiles with multiple warheads. The agreed-upon limit 18 said to be 820. The Soviets otherwise could exceed that number with their present nuclear buildup: the United States force is fixed at 550.

The Soviets have agreed to an equal number of strategic nuclear delivery vehicles, which are bombers and intercontinental missile launchers. The agreed-upon number will be between 2,160 and 2,250. The Soviets are now said to have about 2,500; the United States, about 2,100.

The Soviets have agreed to some limits on their new Backfire bombers. The official would not detail them but reportedly the Soviets have agreed not to raise the Backfire's production rate, now said to be two a month, and not to deploy them in a way threatening to the United States.

The Soviets have agreed that U.S. deployment of up to 120 bombers armed with air-launched cruise missiles would not count against a ceiling of 1,320 on all weapons with multiple warheads.

They have agreed that missiles, such as their powerful SS-18s, that have been tested with multiple warheads shall all be counted as MIRVs (multiple independent re-entry vehicles) regardless of whether every missile of the same type actually carries more than one warhead.

The official concluded at a Thursday background briefing that, under the proposed SALT agreement, the United States could have as much capability as the Soviets to propel tons of nuclear "payload" to the opposite side, as much ability to "kill" missile silos, and as much overall deterrent capability.

Another high administration official, in a background briefing Friday, said a SALT treaty would "give us greater security than no agreement would or if we had gone with the Vladivostok terms." He was referring to an accord reached by former President Ford and Soviet leader Leonid I. Brezhnev that set an overall limit of 2,400 on each side's strategic missiles and bombers.

In recent weeks the Carter administration has been under increasing attack over its SALT posture, and key officials admit a treaty submitted to the Senate any time soon would have trouble setting the required two-third approval.

What provoked last week's flurry of background sessions with press - meetings where officials allow use of what they say but not who they are - was a Tuesday news conference called by Nitze, who was a SALT negotiator himself from 1969 to 1974.

Nitze, who has become a leading critic of current U.S. SALT policy, charged that by 1985 the arms agreement would give the Russians near equality in heavy bombers and a 10 to 1 advantage in land-based intercontinental missiles that can knock out silos promptly.

Nitze also said that with the Soviets' advantage in throw-weight (the ability to propel nuclear payload) and with improved accuracy, their intercontinental missiles could destroy around 90 percent of U.S. Minuteman silos in a nuclear attack.

"I believe we're locked into inferiority and I don't know how you get out of it," he said.

While admitting that the Minuteman system would be vulnerable. Pentagon officials disputed Nitze's conclusion that up to 90 percent of the silos would be wiped out. They said that a Soviet planner could not be sure an attack would get a U.S. missile as well as a silo.

As the nuclear debate escalated, some administration officials were angry over Nitze's release of what one said were "quite accurate" details of the current negotiating positions. Secretary of State Cyrus R. Vance said the release could complicate the negotiating process, but one Pentagon source said he doubted that.

Administration sources agreed, however, that the Nitze analysis provide new ammunition for treaty opponents.