Jordan's King Hussein met with Palestine Liberation Organization Chairman Yasser Arafat for almost three hours tonight in an effort to resolve the deep differences that have emerged between them through a month of crises. But there were no suggestions from the palace following the talks that any clear formula for cooperation had been reached.

Arafat, apparently seeking to put the best face on tonight's encounter, said he had had "very good talks, successful, constructive."

Before the meeting, senior Jordanian officials spoke in sharp terms about the PLO's recent failings, and official statements from the palace were couched in neutral language, underscoring the differences that have emerged since the two leaders put forward a Middle East peace plan in February.

While the PLO called the atmosphere "positive" and "brotherly," the palace made no characterization at all. Its statement said simply that "the latest developments" were reviewed and "an objective evaluation" was made of their impact on the Jordanian-Palestinian peace initiatives.

Measures to "avoid the repetition of similar incidents" also were discussed, the Jordanian statement said. Further talks by working committees are expected Tuesday.

The Hussein-Arafat peace initiative had come under growing strain through a summer of inaction and then a succession of crises in the last few weeks, beginning with the killing of three Israelis in Cyprus in late September. This led to an Israeli retaliatory strike on Arafat's headquarters in Tunisia, followed by the Palestinian hijacking of the Achille Lauro cruise ship and the British cancellation of a much publicized meeting with a joint Jordanian-PLO delegation.

In the wake of these developments, which have dealt a sharp setback to the PLO, Israeli Prime Minister Shimon Peres launched his own peace initiatives at the United Nations. These proposals appear aimed at excluding the PLO, giving still more urgency to today's talks.

Going into the meeting, the PLO was badly weakened, and western diplomats here expected the Jordanians to demand difficult concessions from Arafat and the high-level Palestinian delegation he brought with him.

If not, the PLO faced the implicit threat that it could be barred from Jordan.

If Arafat "doesn't play ball," one western diplomat said, "he's looking at retirement."

But neither Jordanian nor Palestinian officials would cite specific measures Arafat is being asked to take. None would confirm reports by U.S. and Israeli sources that Hussein might try to force Arafat to recognize Israel's "right to exist" and renounce violence.

Such steps would be politically impossible for the PLO at this stage, according to Palestinians here.

Moreover, the presence of the hard-line PLO leader Salah Khalaf in the delegation to the talks, they suggested, virtually ruled out any major concessions of this kind.

Senior PLO officials said earlier in the week that they doubted Hussein would press for such sweeping statements when they would certainly result in an open split.

One senior Jordanian official said this morning: "We would like to see Arafat committed to those elements at the right time, but it is a tactical problem for him right now."

Even one of the PLO's sharpest critics in the palace said earlier today that Jordan "cannot and will not go alone" to negotiations with Israel, as Peres has proposed.

The same official, who asked not to be cited by name, suggested, however, that Jordan would be happy to find alternatives to Arafat as the principal leader of the Palestinian people.

"The problem is that the PLO has no competition," this aide to the king said. But he added, "We will demand that he organize himself in a better way."

The PLO repeatedly has frustrated Jordan's attempts to pin it down on specific issues crucial to the peace process. The Achille Lauro and London incidents suggested a chaotic lack of internal coordination even at its highest level.

"We want to see them behave as real and sincere partners to the peace process," the Jordanian official said. "If [Arafat] is aware of the implicit dangers to the PLO's mission to reach a peace settlement, he can organize himself in a better way."

The PLO has been virtually forced into Jordan's camp by the events of the past three years: first Israel's invasion of Lebanon, then Syrian pressure and an internal schism, and now its own erratic performance during the events of the past month.

The palace official took a cold and calculating view of Arafat's misfortunes.

"In the U.S. view, a weak PLO is dispensable -- completely. Our attitude is that a weak PLO is malleable -- completely. A weak PLO is a good partner for peace," the official said.

Arafat is "in our arms," the Jordanian continued. "We say 'let's move,' but he still doesn't understand this."

"If he wants to do something, he can do it" to further the peace process, this official said bluntly. If not, "nobody is indispensable."

Yet moderate Palestinians visiting here from the Israeli-occupied West Bank questioned this assumption and said they doubted that Jordan soon can find willing or able replacements for Arafat and the PLO.