PESHAWAR, PAKISTAN, MARCH 3 -- U.S. Ambassador Arnold Raphel came here yesterday from his embassy in Islamabad in an effort to reassure worried Afghan resistance leaders of continued U.S. support as negotiations in Geneva to end the eight-year-old war reached a crucial stage, according to a well-informed diplomat.

Raphel "assured them that the U.S. would do nothing to put them at risk, either to a beefed-up regime in Kabul or to Soviet machinations," the diplomat said.

In the U.N.-sponsored peace talks in Geneva today, negotiators agreed that the Soviet Union should withdraw its 115,000 soldiers from the country within nine months from the start of the pullout, The Associated Press reported. Afghan Foreign Minister Abdul Wakil announced his government's agreement to the timetable and told reporters that half of the Soviet troops would leave within the first three months -- an accelerated departure that the United States has urged.

"Nothing important stands in the way of concluding a settlement," Wakil said, although the formation of an interim government including the rival Afghan factions remains an unresolved issue. Soviet leader Mikhail Gorbachev has said the troop withdrawal could begin May 15 if an agreement is signed in Geneva by March 15.

In another development, Zain Noorani, Pakistan's minister of state for foreign affairs, indicated his government may drop its controversial demand that an interim government be established in Kabul prior to signing an agreement on Soviet troop withdrawal. The recent Pakistani demand is now seen as the most critical stumbling block to a final accord.

Under questioning, Noorani told reporters in Geneva that "it is possible that an agreement can be signed before the formation of a transitional government in Kabul," United Press International said.

Moves toward a settlement of the war, however, have brought to the surface the fears of some resistance leaders that the United States has reached a secret agreement with the Soviet Union and will cut off arms supplies to the guerrilla forces at a critical time.

At the same time, the approach of a Soviet troop withdrawal has exposed suspicions among the resistance forces about U.S. and Pakistani policies toward a negotiated settlement.

Perhaps most importantly, the prospects of a settlement have magnified internal political and religious divisions among the seven political groups that make up the Afghan resistance, raising questions of whether the guerrilla forces might fall prey to internal divisions before they can concentrate their energies on a final push to overthrow the communist government in Kabul, should the Soviet withdrawal actually come about.

As one diplomat here explained, "When the focus of the jihad {holy war} was to kill Russians, the religious differences didn't make a lot of difference. When the stakes are different, it comes out."

Assurances similar to those given the resistance leaders by Raphel today reportedly were given them by Undersecretary of State Michael H. Armacost in a meeting a week ago.

Another key diplomat said earlier this week that "a lot of steps will be taken to make sure the resistance has a lot on hand come May 15," the anticipated date of the start of a Soviet withdrawal. Under the accord, arms supplies to the guerrilla forces are to be cut off when the Soviet pullout begins.

Western diplomats portray the guerrilla leaders as worried and uncertain as events take place over which they have no control.

"They are nervous," the diplomat said. "They are worried about mistakes that could be made {at Geneva} about a cutoff of supplies, about the Soviet withdrawal period, that the U.S. would cut a deal that would be against their interests. So {Raphel} came up to reassure them."

An indication of the deep ideological and religious divisions that have developed among the resistance political parties came into the open this week when Zahibullah Mojadidi, nominated by leaders of the seven resistance factions headquartered here as vice president of a new Afghan government, charged in an interview that Ahmed Shah, the presidential nominee, is unfit on religious grounds to hold the office.

Mojadidi complained that Shah "emerged from a party with a Wahhabi affiliation. It has no base in Afghanistan."

Wahhabism is a puritanical Moslem sect that flourishes in Saudi Arabia but has little following in Afghanistan or elsewhere.

While much is made of the Islamic fervor and underpinnings of the war against Soviet forces in Afghanistan, the seven political parties that have been the conduit for most of the weapons to fight the war represent very different strains of Islam.

Of the seven resistance parties, four are considered fundamentalist and three traditional or mainstream Islamic.

Mojadidi comes from the Afghan National Liberation Front, the smallest of the seven and one of the three traditional Islamic parties, and his family has a long tradition of moderate Islamic reform. Others considered moderates are the National Islamic Front of Afghanistan, headed by Ahmed Gailani, and the Islamic Revolutionary Movement of Mohammad Nabi Mohammadi.

Ahmed Shah, the presidential nominee, comes from the Itihad-i-Islami (Islamic Union), headed by Abdul Rasul Sayyaf, which receives most of its funding from Saudi Arabia. Sayyaf follows the strict Wahhabi sect of Islam.

The three larger political parties among the so-called fundamentalists are Burhanuddin Rabbani's Jamiat-i-Islami (Islamic Society) and two factions of the Hezb-i-Islami (Islamic Party), headed by Gulbuddin Hekmatyar and Yunis Khalis.

For a variety of reasons, many of which remain secret because of the covert nature of the war, these three fundamentalist groups have received the bulk of arms supplied by the United States and others through Pakistan.

With the arms have come power and influence. As a settlement and an end to the U.S. arms supply have become possible, the disposition of what is expected to be a final flood of armaments becomes a critical issue for the groups, which suddenly may find themselves facing each other after they have dealt with the communist government in Kabul, if not before then.