When a developing country buys a nuclear power station and agrees to operate it under "safeguards," the task of seeing that no material is diverted to a weapons program falls to the International Atomic Energy Agency.

The IAEA, with a staff of about 1,500 employes, currently safeguards nuclear material in more than 60 countries.

While this ratio may sound comforting, only a relative handful of the IAEA's employes are actually engaged in keeping watch over the nuclear facilities scattered around the world.

Inspectors manage to visit safeguarded reactors no more than several times a year, take a look at the records the country keeps on its inventory of nuclear material and check the film taken automatically by sealed cameras.

"You can't actually stop a country from doing something it shouldn't this way," an IAEA offiial concedes. "Our function is to sound the warning when something has been done."

Some nuclear experts feel, however, that the IAEA has not even been particularly vigilant about sounding warnings.

An IAEA inspection team discovered on a visit to Taiwan in 1976 that 10 fuel rods were missing, and was told they had been taken to another location.

U.S. officials, who disclosed the incident several months later, complained that the inspectors did not demand to see the rods, which cotained plutonium apparently used by Taiwan to test a laboratory-scale reprocessing facility.

The United States has pressed since that incident for a strengthening of the IAEA's safeguards operation, but agency officials view the role of policeman with evident distaste.

"Safeguards can be improved -- and should be improved," the director general of the IAEA, Sigvard Eklund, conceded in an interview. "But you can't have an inspector hanging over the shoulder of every nuclear worker in these developing countries."

Actually, the IAEA does not consider enforcing safeguards its primary function.

Most of the agency's staff is engaged in what the IAEA describes as its principal objective -- "to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world."

Many thoughtful scientists around the world would like to see the IAEA do more policing and less selling.

"The IAEA at present is basically a company for promoting the sale of reactors," Jose Goldemberg, chairman of the Brazilian Society of Physicists, charged. "They do some awful things, like encouraging the Philippines to buy a reactor.

"I am a nuclear physicist, so I am not anti-nuke. And I think in some cases, you can really make a case for nuclear energy," said Goldenberg. "But they promote it so shamelessly when other alternatives exist. To go and spread power plants all over the place just doesn't make any sense."

IAEA officials, for their part, deny that they oversell nuclear power.

"We're not reactor salesmen," a top IAEA official protested. "We do not demote it either."

One function of the IAEA is to carry out market surveys for developing countries to help them ascertain whether they have a need for nuclear energy. Officials find it hard to name many countries that have been advised to forget it.

The potential value of the IAEA has been diminished somewhat in recent years by a growing politicization of the agency.

Taiwan, a developing country with a large nuclear power program, was ousted from the IAEA in 1972 -- though it continues to permit the agency to inspect its facilities.

"For us, the Taiwan situation is a very funny one," an IAEA official admits. "But it must be very comforting to mainland China to know that the U.S. reactors in Taiwan are being inspected regularly."

More recently, the African seat on the IAEA board of directors, which is supposed to go to the country from that region with the highest "level of advancement in nuclear technology," was taken away from South Africa -- which has by far the continent's most sophisticated program -- and given to Egypt.

The superintendent in charge of supervising erection of South Africa's first two nuclear power plants has since been repeatedly rebuffed in his efforts to enroll in one of the IAEA's 12-to-15 week training courses on construction of a nuclear power plant.

After the latest turndown, he was privately advised by an embarrassed IAEA official to quit applying.