A new flood of refugees from Afghanistan in the month since Soviet troops invaded that nation has swelled the total of homeless Afghans in Pakistan to more than 600,000 persons. United Nations officials reported today.

This population already presents Pakistan with the greatest single burden of refugees for any country on the globe, the officials said. And they fear that continued fighting could raise the number of refugees living in makeshift camps and other shelters to one million by spring.

Although they are more numerous than the estimated half-million Cambodian refugees now clustered around the border of Thailand and Cambodia and the 600,000 Ogaden tribesmen who have fled Ethiopia for Somalia, the Afghan refugees have until now attracted little international attention or aid. But they represent a numbing human problem for the region.

Afghans arriving now come in clusters of families and tribes. It took Haji Wali and members of his Ahmadzai tribe 10 days to trek across the mountaions of eastern Afghanistan from their village near Gardez in Paktia Province.

Arriving a week ago at a camp on a rocky plain a few miles west of Peshawar, a city 12 miles from the border, they came not in search of food or shelter, although they need those. Their main concern is weapons, a commodity that the relief agencies are not providing.

"We don't want food, clothes, or money from the big countries," said Sultan Ghani, 50. "We just want guns and machines to use against tanks and airplanes."

Wail, 85, nodded in agreement. It was the second time he has seen his tribe battle a foreign army. The first was in 1919 when he took part in a war against the British.

"Now I'm too old to fight," said the white-bearded Walin, his mottled hands trembling as he told his story. "I save my bullets for the young people."

"This fight is very different" from the Anglo-afghan war of his youth, he said through an interpreter. "Back then, there wasn't a big difference between our fighters and the British. But now the Russians have planes, tanks, and heavy machine guns, and all we have are old rifles."

Nevertheless, the refugees described bloody battles between Moslem rebels and Soviet-backed Afghan army troops in the week preceding the Dec. 27 Soviet coup in Kabul.

In one battle in December, they claimed, rebels cut off a column of tanks at a pass in Paktia Province and killed 17 Soviets they said were accompanying the Afghan force. Three others were captured and marched toward the border with pakistan to be displayed to outsiders, refugees said, but Pakistiani authorities refuse permission for such an event and the rebels machine-gunned their prisoners to death on the Afghan side of the border.

The refugees interviewed at the camp outside Peshawar were unanimous in their explanations for fleeing their country. They said they were bringing their women and children out and seeking arms and ammunition.

"After the Russians came we fought for a few weeks, but our ammunition ran out," said Abdul Jalil, 38, a second-hand clothes dealer from the village of Said Karam in Pakita Province. "We just came here to find some weapons. Then we will go back and fight the Russians.

The provincial Pakistani relief commissioner here estimates that aid provided so far by the United Nations and a few Middle Eastern and Western countries covers only about one-fifth of the refugee population.

The influx is putting severe financial strains on Pakistan, which has been hard pressed to provide about $10 million in direct cash aid. In addition, the presence of the refugees in the rough border areas of Pakistan's North-west Frontier Province and Baluchistan is causing political tensions, with the Afghans growing increasingly restive and local Pakistanis increasingly resentful.

Emergency assistance of $55 million appealed for last week by the U.N. High Commissioner for Refugees is expected to cover only about half of the forecast refugee population.

Some of the refugees expressed disappointment at arriving here to find that, contrary to what they had heard, Western countries were not supplying arms and ammunition to the refugees.

Of the 2,000 refugees at the camp west of Peshawar, about 1,500 are women and children, the Afghans said. There seemed to be few young men among those who gathered around a group of visitors. Most were middleaged or elderly men with turbans and serape-like cloaks, or barefoot boys wearing tattered clothes and frayed skullcaps. Many of the young men, the refugees said, were still in the mountains of Afghanistan waiting for their elders to return with arms and ammunition.

Conditions in the camp were considerably better than those described by refief workers stationed at other camps in remote areas near the border. Some residents had managed to bring cattle, goats and chickens out with them, and those who arrived before last month's Soviet invasion have built thatch huts surrounded by low mud walls.

A major problem is a lack of water, residents said. Women in colorful tribal dress carry jugs of water on their heads from a tap located a mile and a half away. No one seems to be without shelter, although in most cases two or three families share a single tent.

In other camps in restricted Pakistani tribal areas, relief workers have found conditions that one described as "appalling."

Infant mortality is said to be running high. Relief workers estimate it at more than 50 percent, somewhat above the normal rate in Afghanistan, which has one of the highest in the best of times. Besides malnutrition, many children are afflicted with skin diseases because of poor hygiene and lack of water. Many elderly refugees are carrying tuberculosis, which had been brought under control in the Pakistani border regions.

Other refugees are suffering from such ailments as bronchitis and dysentery picked up during their long treks over the mountains.

In one camp, a relief worker said, nine persons died of an infection in one week, and several children succumbed to exposure.

One problem in aiding the refugees is that the limited assistance offered so far by foreign governments and relief agencies often becomes snarled in the awesome Pakistani bureaucray, which insists on handling all distribution. Food delivered to the port of Karachi, for example, can take several weeks to be distributed to refugees. Some relief officials complain about corruption amony low-level Pakistani bureaucrats.

According to an American relief worker, some provincial Pakistani officials have been selling government-issue tents to Afghan refugees for $10 each. Other workers are skeptical about how much of the Pakistani cash aid actually reaches the refugees.

Locally based relief workers also complain that U.N. agencies and foreign governments so far have failed to mobilize enough manpower to handle the influx. One said he thought it was"scandalous" that the office of the U.N. High Commissioner for Refugees had 300 staffers in Thailand but only four in Pakistan. There is also a serious shortage of doctors.

Until this week, there were no women relief workers in the U.N. program to deal with women refugees. Under their strict Islamic customs, the male Afghan refugees do not permit men to examine their women. The first investigation into the state of female refugees here was carried out this week by a team of four French doctors, two of them women.

One quick form of direct aid that has proved immensely popular is handouts by wealthy Arabs from oil rich states in the Persian Gulf.

One such philanthropist, Saudi businessman Sulaiman Rasnied, said he toured 15 camps this week and gave contributions to 50,000 people before leaving Wednesday.