At 6 a.m., a British truck rolls up to the construction site in a cloud of dust. Out scramble Indians, Pakistanis, Yemenis in checked shirts, and a lone Somali.

Farther down the Persian Gulf, thousands of Korean laborers have also begun their day's work, building roads and stringing sewer piping at Jubail, Saudi Arabia.

These scenes are repeated each morning throughout the Arab oil states that line the Persian Gulf.

The employment of foreign guest workers - "gastarbeiters," as the Germans call them - to supplement the local work force is a well documented phenomenon in Western Europe. In the labor-scare 1960s, millions of Yugoslavs, Turks, Greeks and West Africans migrated to Switzerland, France and West Germany to fill menial and service jobs, and work on assembly lines in the expanding factories.

While that tide abated with the economic slowdown of the early 1970s, the quadruping of oil prices has sent a new wave of immigrant labor surging up the Persian Gulf. More than half the work force of the Arab states along the gulf is now made up of foreign laborers.

This new, still largely uncharted phenomenon - by sheer strength of numbers - is having a far greater impact on the Arab gulf states than it ever had on Western Europe.

At the peak, gastarbeiters held only one out of five jobs in Switzerland, and one out of seven in France. In contrast, three out of four jobs in the United Arab Emirates today are held by foreigners.

This new 20th century version of the old skin trade - the export and import of humans - is also having a profound impact on the developing countries that supply the labor.

World Bank economists say Indians and Pakistanis working aboard send more than $1 billion a year back to the families they leave behind. Exported labor has, in fact, become the largest single source of hard currency for Egyptian President Anwar Sadat's financially strapped economy. The million Egyptians working in the oil countries send home almost triple the annual revenue Egypt derives from the Suez Canal.

In all, earnings from the Third World labor trade nearly doubled from $4.4 billion in 1972 to nearly $8 billion in 1975, according to World bank estimates. Some analysts believe the developing countries will earn $11 billion or more from the export of human labor this year.

By comparison, the developing countries earned only $4 billion last year from the export of copper, and $3 billion from the export of sugar, which are among the largest source of their income.

"Relatively little is known about the trends and economic implications" of this enormous trade in human labor, says Zafer Ecevit, of the World Bank's Human Resources Division.

While countries like India and Pakistan, mindful of the need to obtain hard currency to pay back hundreds of millions of dollars in loans to international banks, view the labor trade as a plus, many development economists are frankly skeptical.

Most of the foreign earnings sent back to these countries, they argue, end up being spent in so-called "non-productive investment" on homes and consumer goods.

But for the moment at least, both the gulf Arab states and the countries sending them their workers seem to feel they are benefitting from the arrangement.

"It has become an important form of cooperation between OPEC [the Organization of Petroleum Exporting Countries] and the Third World," says Mohammad Khouja, a senior economist at the Kuwait Fund for Economic Development.

The wave of immigrant labor that has swept up the Gulf since 1973 differs from the migration of foreign workers to Western Europe in that it is far more organized.

The gulf states and the multinational corporations operating here have tended to buy foreign labor the same way they buy miles of pipe, tons of concrete, or hundreds of units of prefabricated housing.

When Iraq's Ministry of Transportation recently took charge of 400 new double-decker British Leyland buses, the government stitched together a companion deal for drivers from Bangladesh.

In Saudi Arabia, Waste Management Inc. of Oak Park, Ill., which has a $200 million contract to handle Riyadh's trash collection, brought in 2,000 Indian Moslems to work as rubbish collectors.

A contractor in Kuwait explained how the labor pipeline works.

A company that wants to bring in gastareiter would apply to the Kuwaiti or Saudi government for visas, often in blocs of up to 500. The company will then contact an agent, perhaps in Pakistan, and tell him it is willing to pay him $350 a head for workers and supply their plane tickets.

The agent makes money both ways, because he also will probably charge the Pakistani workers he signs up $500 apiece - thought this price tends to vary from country to country.

The Pakistani workers are willing to pay for jobs because they will earn anywhere from $10 a day (unskilled to 75 day (highly skilled) on the gulf - far more than they could earn in their own country.

A recent inventory provided by Aramco, the world's largest oil consortium, of its 30,000 contractor employes in Saudi Arabia, gives an interesting picture of the gulf gastarbeiter phenomenon.

Armaco says they include 7,500 Filipinos, 5,700 South Koreans, 2,380 Indonesians, 1,850 Turks, 1,750 Thais, 1,490 Pakistanis and 590 Indians.

While the wages may be good, the life the migrant workers lead in the gulf states is by no means an easy one.

In Sharjah, Pakistani workers building a new shopping mall live in tents next to the work site that offer little relief from the 115-degree heat.

A few blocks from the Kuwait Sheraton Hotel, Indian workers huddle nine and ten to a room in rundown buildings because they cannot afford to live in apartments that rent for $2,000 a month.

In Riyadh, where elegant skyscrapers and apartment buildings are taking shape, gastarbeiters live in squalor in cardboard and scrap lumber shanties.

Earlier this year, there were reports of Indian and Pakistani laborers dying from heat prostration at construction sites in the United Arab Emirates.

The labor-exporting countries, however, have been hesitant to press the Arab states on allegations of abuse, fearful of jeopardizing their chances of getting in on the oil bonanza.

Last year, more than 100 Korean laborers in Saudi Arabia staged a sitdown strike that turned into a riot to protest their working conditions - 10-hour work days and a 28-day work month. Concerned about losing the lucrative contract, the Korean construction firm employing them quickly sent the striking workers home, and apologized to the Saudi government.

Of all the migrant workers, it is the Korean who have made the deepest marks on the gulf.

Two years ago, there were fewer than 100 Koreans in Kuwait. Today, there are more than 10,000. Experts predict that perhaps as many as 80,000 Koreans will be working in the Persian Gulf states by the end of the year.

Saudi grocery stores in Riyadh and Jeddah now carry kimchi, the pickled cabbage, that is a staple of Korean cooking. At Ras Tanura, the Aramco-operated oil part on the gulf, the "no smoking" signs are in three languages - Arabic, English and Korean.

A few of the labor-exporting countries have begun to express concern, however, about the long-term implications of exporting workers - particularly skilled labor.

Adbul Aziz Wattari, a manpower specialist with the Organization of Arab Oil Exporting Countries, says so many Egyptian engineers have been taking jobs in other countries that Egypt could face a shortage of 30,000 engineers by 1980.

Pakistan, concerned about this exodus of skilled manpower, recently tripled salaries in some sectors of its own economy. The Philippines, a relative newcomer to the gulf labor trade, has enacted a law allowing Filipinos to work overseas only for companies registered with the Manila govenment.

But the few clouds on the horizon are largely ignored by the labor importing and exporting countries.

More gastarbeitero - rather than fewer - are likely to be finding work in the gulf in the months ahead.

"They are doing a lot of good for Saudi Arabia," says Saudi Planning Minister Hisham Nazer," and for their own countries as well."