Palestinian sources here say that five Palestinian activists have died from torture or mistreatment and scores of other suspects have been beaten by Lebanese Army soldiers during the past several months. But the Army denies it has tortured anyone and says no one in its custody has died.

The Palestinian charges and Lebanese denials come amid a struggle by the three Western members of the multinational peace-keeping force to gain access to hundreds of Palestinian and Lebanese being held at a detention center at the Army defense headquarters in Yarze east of Beirut.

Despite a Lebanese promise in early October to arrange a visit and repeated requests by the three nations since, the Army has not allowed a delegation of representatives from the U.S., French and Italian embassies into the center.

The Army's refusal to allow any outsiders to visit has made it impossible to determine whether there is any substance to the Palestinian charges. A Western diplomatic delegation that visited a preliminary detention center in East Beirut said it heard complaints of beatings but not of torture and that it saw serious overcrowding.

Western diplomatic sources said France and Italy, whose soldiers have primary responsibility for security in the camps, were the most upset about the reports of torture and mistreatment emerging from the accounts of released prisoners. But all three, including the United States, have agreed to press the Lebanese government to allow the International Red Cross to make regular visits to them, the sources said.

A Lebanese Army official told the U.S. Embassy, after checking, that three of the four Palestinians who allegedly died under torture were still alive and that they had no record of the fourth having been detained.

He did not deny or acknowledge reports that one Palestinian died from mistreatment at the hands of an Army soldier in Gaza Hospital.

Earlier, Lebanese authorities told the three Western embassies that none of the 2,170 persons they said the Army had so far picked up had died in prison or been subjected to "physical torture."

Western embassies and reporters have found no substantiation for recent Israeli charges that the Lebanese Army has killed 1,200 Palestinians and deported 60,000 others. Palestine Liberation Organization officials here deny there is any truth to these allegations.

Apparently hoping to avoid further complications over its status with the Lebanese government, the PLO has so far not made an issue of the treatment of prisoners or sought to give publicity to the alleged deaths.

But there is mounting evidence that many Palestinians, Lebanese and others picked up in the three camps or elsewhere in the capital are severely mistreated, held in extremely crowded conditions and kept in detention without being charged.

The Lebanese Army is still making many arrests in the camps in an apparent attempt to round up all activists from the various Palestinian groups who remained behind after the evacuation of the bulk of the guerrillas in August.

The government, however, has never declared these groups to be illegal or presented any evidence that they are currently a security threat. The PLO still has diplomatic status.

While the 4,000-man international peace-keeping force has prevented Christian militiamen responsible for the September massacres in the Palestinian refugee camps from returning, it has not stopped the Lebanese Army from making widespread arrests nor guaranteed fair treatment of those held for questioning.

How many are being held by the Lebanese Army and security forces is unclear. The government here has provided the United States, France and Italy with a figure of the total number of detainees, which is said to be slightly more than 1,000 out of almost 2,200 it admits to having picked up since mid-September. About half are reportedly Palestinians, a quarter Lebanese and the rest other nationalities.

Palestinian sources here say, however, that they believe the number fluctuates between 2,000 and 2,500 and that most of them are civilians.

Yesterday 500 women gathered at the Aisha Bakkar Mosque in West Beirut to protest the disappearance of Palestinians and leftist Lebanese. Grand Mufti Hassan Khaled has put together a list of 1,324 persons detained or missing.

Palestinian sources and doctors at Gaza Hospital in the Sabra refugee camp have provided the names and some details in the cases of five Palestinian activists who they say have died from mistreatment or torture at the hands of Lebanese security forces or other prisoners aiding them.

The five died between mid-October and Nov. 19, four of them at Yarze and the other at Gaza Hospital, these sources said. The five are Khalid Mohammed Issa Wardi, a member of the youth section of the Popular Front for the Liberation of Palestine; Moussa Khamis, a Palestine Liberation Front official; Kassem Mukahal and Nadim Bibi of the pro-Syrian Saiqa group; and Fuad Hosari, 28, a bodyguard for the Democratic Front for the Liberation of Palestine.

A Lebanese Army official told the U.S. Embassy that Wardi, Mukahal and Bibi are still alive and that the Army is not holding anyone named Moussa Khamis, although he said it did have two people with that last name in detention.

Hosari was killed away from any of the four centers where prisoners are being held, and the official did not confirm or deny his death.

Doctors and officials of the Palestinian-operated Gaza Hospital gave The Washington Post this account of Hosari's death at the hospital:

Hosari, they said, was brought in by three Army soldiers early on the morning of Nov. 19, suffering from wounds.

He had attempted to escape arrest, they said, and was shot twice, once in the back, by soldiers who surrounded his home in Sabra. He was brought to the hospital for treatment and was lying on the X-ray table when one of the soldiers, identified by hospital sources as George Kahwagi, repeatedly banged Hosari against the table, according to Dr. Amir Hamawi, the hospital medical director.

Hosari went into shock and died a short time later, Hamawi said in an interview.

The soldier repeatedly sought to stop the efforts of doctors and nurses to help Hosari, calling him "a dog," doctors said.

Khamis, according to Palestinian sources, died after repeated midnight torture sessions at Yarze.

Wardi, according to Palestinian sources, was tortured to death by a Christian inmate who had been offered freedom by the Army if he participated in the interrogation.

One released prisoner, who asked that his name be kept secret, said the torture methods used by the Army include electric shock treatment and whipping with sticks.

He said that of the 14 persons in his cell at Yarze detention center, only three were not subjected to some form of torture.

A delegation from the three Western embassies was able to visit one Army detention center at Badaro in East Beirut on Oct. 19. Badaro is where most detainees are first taken for questioning before being sent on to the Army headquarters if they are regarded as prime suspects.

One Western diplomat in the delegation said conditions there were "very crowded" but that none of the detainees had complained of torture, though some said they had been beaten. He estimated that 750 persons were being held there.

The biggest complaint encountered, he said, was that the Army was holding many persons for a long period of time after only brief interrogations and for no apparent reason. Hundreds have apparently been in detention since mid-or late September without being formally charged, he said.