Syria today expelled beleaguered Palestinian leader Yasser Arafat in a surprising power move, depriving him of direct contact with loyalist troops as he faces a growing mutiny among his guerrillas in Lebanon.

"You are persona non grata," a Syrian officer told Arafat at the Damascus airport as the chairman of the Palestine Liberation Organization was put aboard a regular Tunis Air flight to Tunisia with only six bodyguards, according to Palestinian sources.

Syria said later that it had ordered the expulsion because of "false accusations" by Arafat that the Syrian government was responsible for increasing attacks on loyalist PLO forces, including an ambush last night in which Arafat said 13 of his guerrillas had been killed or wounded.

Upon arrival in Tunis, Arafat said his expulsion by Syria was "regrettable" and reminded him of his forced departure from Beirut at the height of the Israeli invasion. A PLO spokesman in Tripoli, Lebanon, called Syria's action a "stab in the back" to the Palestinian cause.

A PLO official quoted Arafat as saying upon his arrival that Syria is planning to massacre Palestinians in the Bekaa Valley and the Tripoli area of Lebanon, Reuter reported.

The latest break in often stormy relations between Arafat and Syrian President Hafez Assad was conveyed in a written ultimatum from Lt. Gen. Hikmat Shehabi, the Syrian chief of staff. The message, delivered at 8 a.m., said: "You must leave by 2 p.m." PLO sources quoted Shehabi as saying "We will get you out by force if you do not leave."

Arafat had come to Damascus yesterday from Tripoli, Lebanon, although on Tuesday he had openly accused the Syrians of militarily helping the rebels who for the past seven weeks have defied his authority inside the PLO's mainstream Fatah organization, long his personal power base.

In the past, regardless of what they said privately, Arafat and the loyalists had scrupulously avoided blaming their troubles on Syria. Some observers said Arafat acted because he feared he was losing ground to the rebellion so rapidly that he could effectively rally international support only outside Assad's orbit in Syria and Syrian-controlled Lebanon.

"In view of the continuous slander that Yasser Arafat has been perpetrating against Syria, its sacrifices and positions of principle," said an authoritative Syrian source quoted hours later by the official SANA news agency, "he was told today Syria does not wish him to come into its territory."

A similar ban affected Khalil Wazir, the Fatah deputy military commander also known as Abu Jihad. In Lebanon, he announced he had no intention of leaving in any case, according to state-owned Radio Beirut.

The SANA statement said that despite the government's decision banning the two top Palestinian leaders, Syria would continue "its action to prevent inter-Palestinian fighting, to heal the break and achieve reconciliation between Palestinian brothers."

"This Syrian position of principle is connected with the interests of the Palestinian revolution and the PLO," the statement added.

With only a quarter of an hour to go before the departure deadline, a grimly smiling Arafat emerged from the Damascus PLO headquarters to find his bulletproof limousine surrounded by a half-dozen white Range Rovers crammed with Syrian military police. They made it clear they had orders to storm the PLO office if Arafat had not left on time, according to Palestinian officials.

The Syrians added to Arafat's humiliation by refusing to let him use the private aircraft Saudi Arabia gave him as a gift several years ago. They also refused to let his 25-man entourage fly with him and instead dumped them in Lebanon's Bekaa Valley where the mutiny is going on.

Syria's no-nonsense treatment of Arafat came as a surprise even to key rebel advisers who had predicted he would accuse the Syrians of helping the mutiny as a means of rallying worldwide support.

Arafat spent his final hours in Damascus conferring with top aides--including George Habash of the Popular Front for the Liberation of Palestine and Nayef Hawatmeh of the Democratic Front for the Liberation of Palestine. They were joined by two Soviet diplomats and Algerian Ambassador Saleh Boujamaa, who arrived for a half-hour visit.

Arafat had won Soviet and key Arab support earlier in the month when he left Damascus and traveled to India and a half-dozen Arab states, but Syria--and the rebels--remained unmoved.

Apparently caught unaware by the Syrian decision was Prince Saud Faisal, the Saudi Arabian foreign minister, who had just arrived in Damascus to discuss reconciliation with Assad and flew out 70 minutes after Arafat departed.

Faisal's visit came in answer to Arafat's appeal to a number of Arab countries to help in his difficulties with Syria and it demonstrated, once again, the limits of Saudi influence with Assad.

Similarly, Kuwaiti Foreign Minister Sabah Ahmad Sabah made a brief stopover in Damascus two days ago on a similarly unsuccessful errand.

The abrupt expulsion of Arafat, in the view of observers here, reflected Syria's confidence that it is unchallenged at home and that its foreign adversaries and rivals--whether Palestinians, Israelis or Americans--had little choice but to accept Syrian wishes.

Nonetheless, the timing of the Syrian move was surprising in that only yesterday Arafat had left Lebanon--where he had gone after his first anti-Syrian outbursts--and had met for more than two hours with Rifaat Assad, the president's brother who is considered the second most important man in Syria.

Arafat also saw Soviet Ambassador Vladimir Youkine, who delivered a letter from President Yuri Andropov. Earlier this month Andropov had urged Palestinians to sink their differences and recognize Arafat's "legitimate authority." Arafat told Deutsche Presse-Agentur, the West German news agency, that the letter from Andropov was the "third in 10 days." Andropov was helping mediate the PLO's leadership dispute, Arafat said, "and so are Saudi Arabia, Kuwait, Algeria and Tunisia."

PLO sources said today that the talks between Arafat and Assad's brother had gone well and that Arafat was convinced that Rifaat Assad had signaled willingness to intercede with the president to smooth over their growing differences.

But at dawn today Arafat emerged from a late-night meeting with top Palestinians and accused Syria anew, this time for tolerating what he charged was an ambush not far from Damascus of loyalist vehicles headed toward the northern Lebanese port of Tripoli via the Syrian city of Homs.

That became the only safe route for the loyalists earlier this week when rebels captured several positions on the Beirut-Damascus road.

Arafat said 13 unarmed loyalists were killed or wounded in the ambush by machine-gun and rocket-propelled grenade fire.

Whether those Arafat remarks caused his expulsion remained unclear, but yesterday the three main newspapers in the government-controlled press devoted their front pages to identical denunciations of Arafat's "slanders."

The dispute within Fatah began when some militant commanders and troops accused Arafat of being too closely involved with U.S. efforts to negotiate peace in the Middle East and of failing to pursue military action against Israel.

Through much of the dispute, Syria stayed in the background, insisting it was not "interfering in the arguments between Fatah loyalists and rebels."