Paris — Since the April 1978 communist coup d'etat, the Soviet Union's exploitation of Afghanistan's natural resources has amounted to nothing less than economic pillage.
It is highly probable that Afghanistan's rich natural resource potential was a significant factor in the Soviet decision to invade and now contributes heavily toward subsidizing its estimated $3-$4 million a day military occupation costs.
''It's inclusion within the Soviet orbit is good business for the USSR, which will now seek to exploit (this wealth) and economize on its own resources,'' said J.P. Carbonnel, who headed the last French scientific mission to Afghanistan before it was forced to abandon mineral exploration in the summer of 1979.
Although the communist coup d'etat confirmed the Kremlin's dominance, it was the invasion itself that finally rid the Soviets of the last vestiges of Western competition and gave them a completely free hand in the development of Afghanistan's natural wealth along the lines of a 19th century colonial power.
According to a number of Western development sources with contacts inside Afghanistan and well-placed Afghan government defectors, the Soviets have asserted their control through Technoexport, Moscow's highly specialized development firm, also considered to be an intelligence front.
Wherever possible, development programs, such as the planned expansion of the Afghan hydroelectric grid, are tied into the Soviet Central Asian organization. ''In practice, this will mean that our energy sources will be used to supply the Soviet Union,'' said a senior Afghan engineer who recently defected.
Irrigation projects on Soviet soil using water that should be equally exploited by both countries have been expanded to the detriment of Afghan agricultural development. Furthermore, all exports, whether natural gas, cotton, or dried fruits, are not actually paid for in hard currency but are simply deducted from Afghanistan's rapidly rising national debt to the Soviet Union. The ''purchase'' prices are usually one-half to one-third of world commercial rates.
Since the invasion, the Soviets appear to have concentrated their efforts on Afghanistan's natural gas and oil reserves. At the end of 1978, the Soviet oil research commission in the northern city of Mazar-i-Sharif counted an estimated 2,000 technicians. Within days of the intervention, the Soviets were moving in additional specialists and drilling equipment near deposits located at Dasht-e-Laili, Andkhoi, and Sri Pul in the northern and southwestern parts of the country.
That the Soviets were already at such an advanced stage in exploration indicated they had done their homework well. At the beginning of this year, analysts estimated that $1 billion had been poured into petrochemical development projects alone.
The Soviets have remained highly secretive about their findings, and few reliable details are available. In 1978, the World Bank estimated Afghanistan's oil reserves at a paltry 10 million tons. This was officially upgraded to 14 million tons in 1979 by the Kabul regime.
A year later, a Soviet Embassy news bulletin in Singapore casually noted that Afghanistan possessed large stocks of oil. Several deposits had already been explored, it said, but the fields were not identified.
Since then several senior Afghan government defectors and technicians have maintained that reserves are at least double official estimates. Although many Western oil technicians remain skeptical, some sources have indicated that reserves may be equal to those of Bahrain.
Natural gas exploitation is undoubtedly one of the most striking examples of Soviet economic misappropriation of Afghanistan's resources. Available estimates put its reserves at 120 billion cubic meters, enough to last 50 years at present proposed extraction rates. The USSR first began importing Afghan gas in 1968 (as sole importer) after signing an 18-year contract with extraction rates and prices to be negotiated every year.
At the start, Moscow paid less than one-fifth of the world commercial rate. By the end of this year, the Kabul regime claims it will have exported 2.67 billion cubic meters, roughly double the 1968 amount.
But at $100.34 per thousand cubic meters, Afghan natural gas is pumped into Soviet Central Asia as a cheap form of energy. This permits the Soviets to export Caspian Sea gas, presumably to be followed by Siberian gas, at a much more profitable $180 per thousand cubic meters.
Ostensibly, all petrochemical development is carried out by the Afghan petrol company. But various resistance sources, including a former senior official of the Ministry of Mines and Industries, maintain that the Soviets head all operations, with Afghan engineers working only in a menial capacity.
As with other exports, the Soviets ''pay'' for their gas by simply knocking it off their development ''assistance'' costs such as salaries of Russian geologists and equipment. There is no way of knowing how much gas is being pumped from Afghan reserves, as the recording meters are across the border on Soviet soil.
As for the Afghans, they have to make do with coal and charcoal. By the end of 1980, reportedly not a single cubic meter of gas was being used in Afghanistan itself.
Guerrilla activities, however, have either halted or seriously hampered the Soviet-run development projects in Afghanistan, which number well more than 100.
The mujahideen have repeatedly attacked the Soviet natural gas pipelines leading up to the border. Despite Soviet military surveillance, engineering crews are being constantly rushed in to put out fires or repair damage at blown-up pumping stations.
''At night, fires of burning gas can be seen and smelled for miles around,'' said Haji Morad, an Afghan merchant from Mazar-i-Sharif.
Originally, post-invasion Afghan-Soviet agreements stipulated that 5 billion cubic meters of gas would be piped to the USSR per year. In 1980, however, production officially represented only 1.12 billion. Despite government assertions, this year's balance may be hardly any higher.