PESHAWAR, PAKISTAN -- Western aid workers and journalists in Afghanistan have come under attack in recent months, apparently by Afghan rebels, raising fears among Afghans and diplomats of new fissures within the anti-Soviet Afghan resistance alliance.

Reports of the attacks -- and of recent confrontations between Afghan resistance groups -- remain blurred by rumor and conflicting claims. However, Afghans, Pakistani intelligence officials and foreign diplomats said in interviews that most of the incidents have been traced to one of the seven main Afghan resistance parties, the Hezb-i-Islami led by Gulbuddin Hekmatyar.

Hekmatyar holds strict Islamic fundamentalist beliefs and has close ties to fundamentalist groups in Pakistan and the Middle East. He has expressed adamant opposition to any accommodation with the Soviet-backed People's Democratic Party in Kabul, a step that many non-Afghan analysts see as necessary at least in the short run to get a Soviet commitment to withdraw troops.

Diplomats based in Pakistan have said they believe Hekmatyar has received a significant portion of U.S.- and Arab-supplied weaponry for use against Soviet forces. Pakistani sources said he has been stockpiling arms in recent months, reinforcing reports from diplomats that field commanders are complaining about not receiving promised weapons and ammunition.

The sources who spoke about the reported attacks by Hekmatyar's forces left it unclear whether Hekmatyar has ordered them directly, or whether they have been conducted by undisciplined local commanders inside Afghanistan.

According to diplomats and other observers, the incidents over recent months have included:

The waylaying of at least two French medical groups attempting to get badly needed supplies and money for the purchase of food to resistance commanders in Afghanistan's interior. Tens of thousands of dollars in supplies and monetary aid were taken.

The harassment of several journalists, including thefts of cameras and film.

The apparent death of veteran free-lance film-maker Andy Skrzypkowiak, who was working on contract with the British Broadcasting Corp. He was last seen in mid-October in the northeastern province of Nuristan, being pursued by four men belonging to a local Hezb-i-Islami unit. The four, also believed to have been involved in robbing one of the medical caravans, later were detained by Pakistani police, who have released no results of their investigation.

Hekmatyar and his aides have consistently denied any such activities, although they express disdain for many activities of western aid workers and journalists who do not cooperate with their group.

"The groups that took the cameraman inside should be asked, not us," Hekmatyar said in a recent interview. "Only real journalists travel with us and not intelligence agents in disguise."

During the early years of the resistance movement, there were persistent reports that Hekmatyar and other fundamentalist leaders in the resistance were trying to limit the activities of westerners in Afghanistan, claiming their presence tainted the Islamic character of the movement. Medical teams, especially those that included women, often were targets of harassment.

"The people who did a number of these things {recently} have operated in an area that is under one of his {Hekmatyar's} commanders. What is not clear is who ordered them. There is some evidence that a few small groups may have gone off on their own," said a diplomat who followed these events closely. The diplomat agreed with others, however, who said they tend to believe that there is some link between the incidents and Hekmatyar's headquarters near here.

"It is a sorting out {among} the fundamentalists, {who are} trying to establish themselves as the stronger units as some kind of a political solution approaches," said a close observer of the Afghan rebels' politics. "We are seeing the influence of the Saudis and the Iranians with {Hekmatyar's} Hezb, a resurgence of the fundamentalists and their antiwesternism," the observer said.

"We can't say it is all centrally directed. There always is an element of banditry in a wartime situation and especially {in} Afghanistan . . . . But this is different."

Others argue that the conflict is a narrower one, between Hekmatyar and Ahmed Shah Massoud, a powerful and highly publicized local commander based in the Panjsher Valley of northeastern Afghanistan. Most of the medical and financial aid and the journalists who have been waylaid were headed for Massoud's territory.

Massoud is part of Burhanuddin Rabbani's Jamiat-i-Islami party, which, like Hekmatyar, is rooted in the growth of fundamentalist Islam among students and intellectuals in Kabul in the 1960s. But Rabbani's party is seen by independent Afghan observers as the most moderate of the four fundamentalist resistance groups.

Last August, in a revival of the type of incidents reported often in the early years of the anti-Soviet guerrilla war, eight mujaheddin, or guerrilla fighters, from Rabbani's group were kidnaped and imprisoned by Hekmatyar's guerrillas after they refused to fight for Hezb-i-Islami, according to Pakistani sources.

When Pakistani security forces went to Hekmatyar's main camp to force the release of the eight, an armed confrontation reportedly was narrowly averted. The eight finally were released.

Hekmatyar also is reported to have challenged the right of a rival party, also called the Hezb-i-Islami, to assume overall command of fighting around the strategic Afghan government garrison at Khost, in eastern Afghanistan. Starting last month, Soviet forces led an offensive to relieve Khost.

"We are better equipped and have a far better fighting force in the Khost area" than the rival Hezb, Hekmatyar said in an interview. Independent observers, both Afghan and foreign, believe that the other Hezb-i-Islami, led by Yunis Khalis, and a third resistance party are dominant in the area.

Official sources in Peshawar confirmed that, after an escalation of bomb blasts here several months ago, a large number of Hekmatyar's men were taken on by the Pakistani security services to help watch for infiltrators working for Afghanistan's secret police. "By the end of last year the police had to get rid of most of them because they were found to be passing on information about members of other guerrilla groups," said one official.

Special correspondent Kamran Khan contributed to this report.