he Palestine Liberation Organization initially claimed responsibility tonight for a grenade attack that killed an Israeli soldier in Gaza but then reversed itself and said it had nothing to do with the incident.

The confusion resulted in reports on international news agencies and radio stations setting down PLO responsibility--disclaimed only later--against a background of repeated Israeli threats to attack PLO forces in Lebanon if any Israelis are killed in guerrilla raids. It dramatized the predicament of the guerrilla movement, eager to get involved in the growing West Bank crisis but reluctant to be seen giving Israel a reason for launching an attack.

The backing and forthing, unusually serious amid the tension generated by the West Bank disturbances, also demonstrated the difficulties faced by PLO Chairman Yasser Arafat in exercising control over the eight disparate factions under his PLO umbrella.

Arafat's PLO executive committee, after an emergency meeting on the problem of the West Bank that took all afternoon, issued a communique hailing the uprising there and charging that Israel's firing of two more mayors was part of a plan to impose direct Israeli administration on the area, captured in the 1967 war.

In a conclusion that seemed to underline Arafat's caution, the communique said: "The PLO executive committee, as it assumes its responsibilities in action on various levels in these dangerous and delicate circumstances, took a number of decisions and measures to assure broad support for the uprising of the masses and the indefinite strike and achievement of the broadest Arab and world support for this struggle."

The communique made no mention of what the measures are. The reference to "dangerous and delicate circumstances" seemed to refer to the numerous warnings from Defense Minister Ariel Sharon and other Israeli leaders that any PLO action that leads to Israeli deaths would be considered a reason for attacking guerrilla forces in Lebanon.

In the same spirit, the communique ignored the grenade attack in Gaza. In the meantime, however, the Democratic Front for the Liberation of Palestine, a PLO member, had issued its own statement claiming the Gaza attack was the work of one of its clandestine commando groups.

Within hours--at about the time the PLO leadership meeting was breaking up--Democratic Front spokesmen began calling news offices in Beirut to say the operation was no longer claimed by their group only, but by the general PLO command under Arafat. By then, the earlier claim had been broadcast on Middle East radios.

Mahmoud Labadi, the PLO spokesman, confirmed after checking with guerrilla officials that the PLO command was indeed claiming official responsibility "in the name of the Palestinian people." PLO sources contacted at the same time, however, advised correspondents to take the claim with a grain of salt and avoid making it a major news item.

"A kid threw a bomb in Gaza," said one PLO official. "It's just a bomb. I doubt if anybody here knew in advance it would happen. Somebody threw a bomb."

The various statements suggested that Arafat's PLO leadership was upset at the Democratic Front claim but unwilling to get into a dispute with the Marxist-oriented guerrilla group by denying it outright. Instead, the officials sought to lead inquiring reporters to the conclusion that the PLO responsibility claim was merely a formality.

About half an hour later, however, Labadi reversed himself and officially disclaimed PLO responsibility for the Gaza attack. A special late bulletin from the PLO news agency WAFA on the violence, datelined "occupied territories," reported the incident by saying only that "a grenade was hurled" at an Israeli vehicle.

The muddle, although apparently due in part to simple lack of coordination, underlined the atmosphere generated among Lebanese and Palestinians here by repeated Israeli threats of a massive attack against guerrilla targets. Reports of the West Bank disturbances have been followed with extraordinary attention because of these fears.

Heeding a Palestinian call, owners of some Beirut businesses closed their shutters for a one-hour solidarity strike today. The movement was widely followed in the Lebanese capital's Palestinian quarters. But only a few shops closed in the mostly Moslem Hamra commercial area and almost none in the Christian half of the divided city.

Businesses in Amman and Damascus, following orders from the Jordanian and Syrian governments, were reported to have observed the strike widely and the Syrian state radio broadcast nationalist poems and music in support of striking West Bank Palestinians.

Abdul-Aziz Hussein, a Kuwaiti cabinet official, called on the United Nations to order a halt to Israeli actions in the occupied territories. His call was backed by Habib Chatti, secretary general of the Islamic conference, who accused Israel of laying groundwork for annexing the area.