Western European political leaders today used harsh words to condemn the alleged shooting down of a South Korean jumbo jet by the Soviet Union but also expressed hopes that the incident would not jeopardize tentative moves to improve East-West relations.

Soviet ambassadors in at least four West European capitals were called in to foreign ministries and asked to provide a full explanation of the disappearance of the jetliner. But they appear to have provided few new details, and the Soviet Embassy in Paris issued an angry statement accusing the United States of unleashing an "hysterical anti-Soviet" propaganda campaign.

The Soviet Embassy's statement, in a translation by The Associated Press from the French-language original, read:

"What is concerned is a catastrophe of an aircraft which, furthermore, twice violated the airspace of the Soviet Union. For two hours the crew of the aircraft did not reply to insistent signals addressed to them in ways conforming to the universal international aerial code.

"The hysterical anti-Soviet campaign unleashed as if by signal by the Americans is absolutely unacceptable. It is even more incomprehensible that France has let itself by swept up in it without having its own independent information as to what took place."

In the view of most political commentators in Western Europe, it is still too early to judge the long-term political and diplomatic consequences of the affair. Much depends on whether the Kremlin sticks by its present policy of riding out the Western protests or accepts the apparent responsibility for the shooting down of the Boeing 747 and offers to pay compensation to the victims.

Several West European leaders said that it was in Moscow's own interest to provide a full explanation of the incident as this would help to relieve public pressure for tough countermeasures by the West.

Pacifist groups around Europe reacted with horror to the incident, which was described by the West German Greens Party as "a cold-blooded mass murder carried out with military precision." But they have given no sign of reconsidering protest actions against the scheduled deployment of U.S. intermediate-range missiles in several West European countries.

At the European Security Conference in Madrid, diplomats went ahead with plans to receive foreign ministers from 35 countries, including the United States and the Soviet Union, next week. A spokesman for the U.S. delegation said a meeting between Soviet Foreign Minister Andrei Gromyko and Secretary of State George P. Shultz was "more important than ever," but others expressed concern that it might now be in jeopardy.

In Paris, French officials said that a visit by Gromyko scheduled for next Monday would still go ahead but that French Foreign Minister Claude Cheysson would use the opportunity to press for a more complete Soviet explanation. The British foreign secretary, Sir Geoffrey Howe, said he also hoped for an early meeting with Gromyko. But the Dutch government said it was reconsidering a visit planned for Sept. 13 by a Soviet deputy foreign minister.

In a radio interview, Howe said that the world was bound to reflect "what kind of government and society it is that allows this kind of thing to happen." He said that the shooting down of the plane could set back the prospects for arms-control talks in Geneva but insisted that the West retained an "important interest" in pursuing them.

The British foreign secretary said he had expressed the Conservative government's "strong condemnation" and "horror" at the incident during a 30-minute meeting with Soviet Ambassador Victor Popov. France, West Germany and the Netherlands also called in Soviet envoys to make similar protests.

The Vatican announced that Pope John Paul II had sent a telegram of condolence to South Koreans in which he expressed "shock" at the tragedy but made no direct reference to the Soviet Union.

Addressing a conference on world security in Stockholm, Swedish Prime Minister Olof Palme said the incident could lead to "a further sharpening of the already tense international situation." But he later told The AP that neither the shooting down of the Boeing 747 nor intrusions by Soviet submarines in Swedish waters had lessened his commitment to improving East-West relations.

Antinuclear protesters who have been disrupting traffic at a U.S. Army base in the West German town of Mutlangen issued a statement saying they were "shocked, incensed, and saddened" by the Soviet actions. The statement added that the threat of weapons of mass destruction made detente essential to attain "total neutrality for Germany."

The loss of the Boeing produced banner headlines in newspapers throughout Western Europe, with Amsterdam's De Telegraf calling it "a ghastly and unprecedented act of terror." Newspapers in France all devoted several pages to the incident, and some speculated that an order to shoot the plane could have been given by hard-liners in the Soviet armed forces with the deliberate intention of worsening East-West relations.

The independent leftist newspaper Liberation here described the initial, tight-lipped Soviet response as "an act of sovereign contempt for the rest of the world" and a "caricature" of the Kremlin's own worst image. The conservative France-Soir said in an editorial, "This sort of thing is called murder."

The influential daily Le Monde referred to the precedent of the shooting down of an Israeli plane by Bulgaria with the loss of 58 lives in 1955. The paper said that the present diplomatic storm would blow over fairly rapidly if the Soviets followed the Bulgarian example by expressing regret and paying compensation. It added, however, that attempts by Moscow to continue to deny responsibility could have "very grave consequences" and lead to "a cycle of reprisals."

In several West European capitals, including Paris, security was discreetly reinforced around Soviet buildings.