The Palestine Liberation Organization's besieged military leader in Lebanon said today that Syrian-backed PLO rebels have executed two loyalist fighters and have imprisoned more than 20 others whom they kidnaped in recent days.

But he and other guerrillas loyal to exiled PLO leader Yasser Arafat appeared to be concerned less about the violence itself than about what they regarded as Syrian efforts to topple Arafat by convincing PLO fighters on the front lines that he is finished.

Khalil Wazir, better known as Abu Jihad, Arafat's soft-spoken deputy military commander, talked to reporters at a refugee camp in this port city in northern Lebanon, the last stronghold of Arafat loyalists. It was his first such session since he fled Saturday from the front lines in eastern Lebanon's Bekaa Valley, where Syrian troops have encircled PLO positions and put tanks around military headquarters.

Abu Jihad acknowledged that Syrian authorities had ordered him to leave Lebanon when they expelled Arafat from Damascus Friday, but he vowed to stay with the loyalist fighters, although he was vague about how he would return through the reinforced Syrian mountain positions separating this loyalist beachhead from his command post in the Bekaa.

Firmly ruling out for now any plan to lead his outnumbered guerrilla forces against a Syrian Army reinforcing its troops and armor daily, Abu Jihad said he and Arafat were hoping that the situation would be resolved by Arab diplomatic efforts to settle the dispute with Syria and by their own plans for meetings aimed at ending the revolt within the PLO.

"Even though the circumstances may be difficult," he said, "we have our hopes. We have our way and we are stressing on always being ready to face all difficulties."

Abu Jihad avoided the kind of slashing rhetoric about the rebels and the Syrians that he and Arafat had used before the expulsion. He said he and Arafat would welcome the rebels back into the fold and were looking for ways to end the rift with Syria.

Abu Jihad said two Arafat loyalists whose bodies were recovered three days ago in the Bekaa were among the fighters kidnaped at jointly manned Syrian-rebel checkpoints in eastern Lebanon near the Syrian border.

Abu Jihad said that although some who were seized during the last week and a half have been released, rebels were still holding more than 20 others in makeshift prisons, including a converted horse stable in the Bekaa.

A 36-year-old Lebanese who is a fighter with Arafat's forces said in an interview that he escaped from the rat-infested stable last week after enduring beatings by guards.

He said the guards there were from the Popular Front for the Liberation of Palestine--General Command, a radical, Libyan-financed splinter group in the PLO whose leader, Ahmed Jibril, has long been in conflict with Arafat.

He has joined forces with the more moderate Col. Said Musa, also known as Abu Musa, who has called for reforms within the PLO and the resumption of armed struggle against Israel.

In the view of Arafat's aides, however, what is more threatening than the executions and incarcerations are Syria's actions in separating PLO leaders from their troops in the Bekaa Valley, encircling the guerrillas and mounting a media campaign against Arafat.

Syrian official statements claim impartiality in the two-month-old mutiny within Fatah, the PLO's largest faction and previously Arafat's main base of support.

Arafat aides here were especially wary today about the Syrian decision to allow remarks by Abu Musa to be reported by SANA, the official Syrian news agency, and heard on state-run Damascus Radio. They said Arafat never has been interviewed by the government-controlled Syrian press in all his 15 years as PLO chairman.

Abu Musa reiterated a call for Arafat to resolve the PLO dispute by convening a congress of Fatah.

The rebels' spokesman and leader is not believed to have been able to bring over large numbers of Fatah fighters to his side and is thought to be heavily dependent on the Syrians.

"They are giving the rebels cars, supplies and ammunition," said one Arafat adviser. "They want to take apart our forces piece by piece."

The loyalists' major effort has been to counter Syria's words with their own. Recently a pro-Arafat newspaper resumed publication here, and an effort is being made to get a radio station, "Voice of Palestine," on the air to reach the troops in the Bekaa.