TRIPOLI, LIBYA, AUG. 20 -- Libyan leader Col. Moammar Gadhafi said tonight that he opposes Iraq's use of foreign hostages as human shields against an attack by U.S. forces in Saudi Arabia, and that if the United Nations votes to enforce a naval blockade against Baghdad, he would support the move with Libyan forces.

Gadhafi sharply criticized U.S. moves to impose a naval blockade without U.N. approval. He also said he had been attempting to contact President Saddam Hussein but that communications had been cut and he was unable to give the Iraqi leader his views on the 11,000 foreigners trapped in Iraq and occupied Kuwait.

"I am against using civilian workers as hostages. I'm against such bargaining," Gadhafi said at a news conference in a tent less than 100 yards from the house that was heavily damaged when U.S. F-111s attacked it in April 1986, in retaliation for the Libyan-inspired bombing of a West German discotheque filled with U.S. servicemen.

Gadhafi's 2-year-old adopted daughter was killed in the bombing, but the Libyan leader was not inside the building at the time.

Revising his earlier position on the Persian Gulf crisis, Gadhafi repeatedly noted that the U.N. Security Council had condemned the Aug. 2 Iraqi invasion of Kuwait. He suggested that his only quarrel with that condemnation was that the United States had rendered it meaningless by effectively enforcing a naval blockade on its own.

When asked if he would support a naval blockade if one were approved by the Security Council, Gadhafi replied, "Yes, of course."

Gadhafi said, "If the U.N. Security Council agrees on the application" of blockade enforcement, "it will be up to the U.N. to define what peace-keeping forces to send to do that. If the U.N. Security Council chooses Libya as one of those countries, Libya would, of course, abide by the resolution."

When the Arab summit meeting in Cairo on Aug. 10 voted to condemn the Iraqi invasion and to send an Arab force to Saudi Arabia to defend the kingdom against a possible attack, Gadhafi voted against the resolution, along with Iraq and the Palestine Liberation Organization.

A week before, Gadhafi and PLO Chairman Yasser Arafat advanced a joint "peace initiative" that was widely viewed in the Arab world as an attempt to scuttle an earlier Arab summit meeting planned for Jiddah, Saudi Arabia, but that was canceled because of divisions among the Arab leaders over the peace plan.

Gadhafi, who in the past was looked on as a more radical leader than Saddam, summoned journalists on short notice from Paris, Cairo, Tunisia and Malta. He was sharply critical of the United States for enforcing a naval blockade, and at one point he said he was thinking of withdrawing from the United Nations because the U.S. action had rendered it meaningless.

"If . . . America wants to act on behalf of the United Nations, there's no point in maintaining membership anymore," Gadhafi said. However, when asked what he would tell Saddam if he was able to talk with him now, Gadhafi replied, "I've always said, Iraq's entry into Kuwait is condemned. However, the U.S. entry into Saudi Arabia has spoiled everything and given Iraq justification."

Gadhafi said the United States has a "very weak position" in the gulf dispute because of its invasion of Grenada in 1983 and of Panama last year.

While he did not directly say so, Gadhafi appeared to favor the application of some sort of sanctions on Iraq. He said, "The United States and its allies did not give us a chance to do so. They applied Article 42," of the U.N. Charter, which could authorize a blockade, while the U.N. Security Council called for economic sanctions under Article 51.

The hour-long news conference frequently erupted into shouting matches among reporters as Gadhafi, dressed in a silk suit and open-neck shirt, looked on and waited for order.

At one point, Gadhafi said, almost defensively, "I'm not trying to defend Iraq's entry into Kuwait, because this is something that was condemned by the Arab League and the U.N. Security Council." Gadhafi several times reminded his questioners that Libya is still a member of the United Nations and respects its charter.

"We are very much concerned to see that the U.N. Charter is respected and observed by everybody," he said in voicing his objections to the U.S. military actions against vessels in the gulf suspected of transporting cargo to and from Iraq.