Beirut — PLO chairman Yasser Arafat may soon be a general without any troops. Rebels from Mr. Arafat's Fatah faction of the guerrilla movement are on the verge of eliminating the positions and top personnel of loyalist troops struggling to hold out in bases in Lebanon's eastern Bekaa Valley.
In a bold and methodical campaign over the past 10 days, rebel leader Abu Musa and his mutineers have seized all the main bases in the valley floor and now appear to be consolidating around the last two loyalist strongholds.
Militarily the move, which has featured a series of intense and bloody battles, was unnecessary, since the loyalists were already besieged and cut off from supplies. And Mr. Arafat has admitted his troops do not have the arms or numbers to launch counterattacks against Syrian tanks and artillery, which have backed up the rebels.
The rebel offensive appears to have a political goal which is timed to the emergency meeting of the PLO executive committee in Tunis. Arafat called the meeting to seek endorsement of his leadership from members of all eight factions and Palestinian independents.
Arafat supporters dominate the 15-member committee. Only two committee members are known to be actively supporting the mutiny aimed at radicalizing PLO policy. But several are neutral and have tried to mediate an end to the rift between Arafat and Syrian President Hafez Assad, whose support for the extremists made the mutiny possible.
The rebels hope events on the ground will influence the executive committee's decision or even overtake it. It would be difficult for the group, in effect the PLO's Cabinet, to endorse the leadership of a man who cannot control his own faction. They may resist taking a final vote.
Rebel spokesmen have made it clear that they intend to rout the supporters of Arafat. Abu Salih, the leading political figure in the mutiny, issued a statement declaring, ''We shall purge the ranks and take everyone to account, no matter how senior they may be. Those who have undermined the rights of our people will not go unpunished.''
Abu Salih also attacked Naif Hawatmeh, chief of the Democratic Front for the Liberation of Palestine faction, as another figure who had betrayed the Palestinian cause by agreeing to mutual PLO-Israeli recognition. Mr. Hawatmeh and Dr. George Habbash of the Popular Front for the Liberation of Palestine (PFLP) - who lead the next two largest PLO factions - have publicly remained neutral, although in private they have tried to aid Arafat.
Indeed, the mutiny this week openly splintered the entire guerrilla movement. Two pro-Syrian factions that had earlier aided the rebels have gone public with their positions. A statement from the PFLP - General Command said: ''The present leadership of the PLO as represented by Yasser Arafat and his rightist group is no longer capable of exercising the leadership role for the Palestinian revolution and people, and does not inspire confidence at this critical phase in the history of the struggle in the region.''
Although Abu Musa has claimed that the mutiny was aimed only at winning a larger role for the dissidents and their militant strategy, Arafat and his top aides say the rebels are out to discredit and then eliminate the PLO leader politically, and that can best be done by cutting the ground out from under him.
In what may turn out to be the final chapter in the saga, rebels and their Syrian backers are doing exactly that, swiftly and mercilessly.
PLO sources and Beirut observers claim many Fatah loyalists captured during the fighting last week were subsequently executed. Others have been interned in makeshift concentration camps. And loyalists have admitted the capture of Col. Nasser Yousef, commander of the Yarmouk brigade, the largest section of Arafat's best men.
There are growing indications that the rebels may next attack loyalist bases around the ancient city of Baalbek, and finally the northern port city of Tripoli, where Arafat set up new operational headquarters this month.
The rebels have consolidated around Baalbek, while Western sources claim Syria has sent in reinforcements, tanks, and artillery over the past two days to their positions on the outskirts of Tripoli's two Palestinian camps.
It is the Syrian involvement that has allowed the rebels to move so fast and effectively, since loyalists are still considered to outnumber them. Yet Syria continues to deny its primary role, alleging any actions are only a response to ''slander'' and a pressure campaign by Arafat, aimed at ''ruining Syria's reputation.''
Assad also continues to ignore pressure from the Arab world and the East bloc to stop the fighting and killing within Arab ranks; he has almost gone too far to relent on a tactic apparently designed to topple Arafat.
Without Arafat on the scene, the Syrian leader stands to gain much, including a shift in the approach to Middle East peace proposals. Assad would effectively take over the kingpin position from moderates, particularly King Hussein of Jordan, and be able to demand terms and aims more favorable to his beleaguered nation.