Disclosures in the American press that the Central Intelligence Agency is providing about $250 million in covert aid this year to anticommunist insurgents in Afghanistan have triggered bitter feuding among the Afghan guerrilla groups headquartered here.

Skeptical leaders of rival mujaheddin forces said they have not seen a fraction of that amount in supplies cross the porous border between Pakistan and Afghanistan, and they accused one another of siphoning off shipments and selling them for personal profit.

One resistance leader estimated that only about 20 percent of the weapons that move along a circuitous route through the Middle East and Pakistan actually reach the beleaguered resistance fighters in Afghanistan. Much of the rest, he said, is being sold by a few corrupt guerrilla leaders based here to leftist groups opposed to the government of Gen. Mohammed Zia ul-Haq and even peddled in the arms bazaars of the Northwest Frontier Province to the Afghan fighters to whom it was originally consigned.

While squabbling among ideologically diverse rebel organizations -- sometimes leading to fierce fighting here and in Afghanistan -- is not new, the disputes over money and arms have reached a new level of intensity as a result of reports published in The Washington Post and The New York Times that Congress has nearly tripled the Reagan administration's original request for covert aid to support the rebels' five-year-old war against Soviet occupation troops in Afghanistan. The estimated $250 million expected to be provided the rebels this fiscal year is part of the largest CIA military-support operation since the Vietnam War.

Leaders of the political wings of the rebel groups and some of the field commanders who recently returned to Peshawar from what has become a commuting war expressed incredulity in interviews when asked whether reports that they had received a total of $625 million in U.S. aid since the 1979 Soviet invasion were accurate.

Ahmed Bashir Faheen, a commander of three guerrilla districts in Kabul Province who came here to recover after he was wounded by a Soviet tank gunner, laughed sardonically and said, "We see no trace of this aid in the camps or at the front. We are hearing things that we don't see in action. If these things were true, the Russians would have been driven out by now."

He said his fighters were underfed, poorly clothed against the harsh winter and often reliant on Kabul businessmen who contribute supplies to the guerrillas while risking arrest by Afghan police. He estimated that only about 50 percent of his unit's food and clothing come from Pakistan.

Another Kabul-area guerrilla commander, who arrived here Monday from the front, questioned whether the U.S. military aid reports were true. "It might have come to the pockets of those selling arms in the Pakistan market, or it might have gone to those who are not important in the jihad Islamic war against nonbelievers . Maybe it is a fiction of those people who are blowing their own trumpets in the West," he said.

Faheen, whose units are attached to the fundamentalist Hizbi Islami group headed by Gulbaddin Hekmatyar, questioned whether any of the sophisticated weaponry that purportedly is being shipped, such as antitank rockets, antiaircraft cannon and an improved version of the shoulder-fired SA7 surface-to-air missile, is reaching the guerrillas. "I haven't seen any trace of it in my areas. We see that other groups get advanced weapons that are sold on the Pakistan border. They are going to arms dealers and not the mujaheddin.

"The resistance has been sustained on ideology and faith," he added. Those who are motivated by the jihad will continue to the end anyway. But those who fatten themselves by selling this equipment will not."

Faheen did not specify which groups he thought were skimming U.S.-purchased supplies, but Mohammed Salim, a member of the Hizbi Islami's political commission, said the three guerrilla groups comprising the Moderate Alliance -- the Revolutionary Islamic Movement, the National Liberation Front and the National Islamic Front -- were involved.

"They are nothing more than politicians and businessmen. They aren't fighting in Afghanistan. They are comfortable in big villas in Peshawar. They sell 80 percent of the arms to the enemies of Pakistan," Salim said.

For their part, leaders of the moderate groups complained that fundamentalist rebel groups were being favored in the distribution of weapons supplied by the United States and several Middle Eastern countries, reportedly including Saudi Arabia, Kuwait and the United Arab Emirates, and funneled through Karachi and other ports under the guidance of Pakistani authorities.

"Most of the arms are given to extremist groups, and some of them are not fighting the Russians. They are fighting the mujaheddin. Their stores are full of weapons, here and in Afghanistan. They don't have enough men for those weapons," said Sibghatullah Mojadidi, president of the three-party Moderate Alliance.

A leader of one of the moderate groups, who asked not to be identified because, he said, Pakistan ostensibly is not involved in the arms pipeline, said, "We don't know how many weapons are coming into Pakistan, but we do know we get only one-tenth of what is coming."

He bitterly denied the accusations of corruption made by the fundamentalist groups, saying, "You would only sell weapons if you had more than you need. We don't even have enough. They the fundamentalists sell truckloads in our name. They are the ones who are corrupt."

The Moderate Alliance, however, has been shaken by dissent. A petition signed by 300 of its members last week complained to the leadership of financial mismanagement and inequitable distribution of money.

Mojadidi denied that the petition was connected to distribution of supplies to the front and said it had been inspired "by subversives" linked to the KGB, the Soviet secret police.

"There were some corrupt individuals in the alliance a while back, and we kicked them out. Now they are trying to create disturbances. For three years we were stable and unified, and the KGB was concerned. Also, the extremists fundamentalist alliance groups are jealous," Mojadidi said. He added that some members signed the petition because staff salaries had been cut by half one month and by two-thirds the next as a result of cash-flow problems.

Guerrilla leaders refused to discuss details of the pipeline through which enough supplies to maintain approximately 200,000 full- or part-time rebels must flow, but U.S. intelligence sources describe it as a maze of intermediaries designed to cover direct links to the U.S. government, with little or no accountability. Afghan exiles trained by the CIA are said to receive Soviet-made AK47 rifles, mortars, rocket-propelled grenades, surface-to-air missiles and other weapons through purchases made from Eyypt, China and, in the case of captured weapons, Israel, and then repack them in containers bound for Pakistan from several Persian Gulf states.

Pakistani agents at Karachi and other entry points reportedly shepherd the shipments around customs, and they are trucked to distribution warehouses near the border in Baluchistan and Northwest Frontier provinces. Pakistan is given full control of the shipments because it is risking Soviet retaliation, and some of the supplies are siphoned off before reaching the border, according to intelligence sources.

Hekmatyar, whose guerrilla groups currently are engaged in heavy fighting in Paktia and Konarha provinces close to the Pakistani border, complained that the focusing of public attention on the weapons-flow controversy was undermining the resistance movement.

"The policy of the Pakistanigovernment is to declare that its soil is not used as conduit of arms. Those who make such claims, what are they driving at . . . ? This propaganda will give the Russians a chance to justify the occupation of our country," Hekmatyar said in an interview.

However, pressed on the question of disparity between the amounts of weapons shipped and those that reach the front, he said, "Those who are fighting more will need the weapons. Those who are not fighting at all will sell them on the market. Those who can't use the weapons will waste them."