Professors from Harvard and the Massachusetts Institute of Technology (MIT) are serving on a White House committee investigating reports that South Africa detonated a nuclear explosion on September 22, the director of the Center for Astrophysics (CFA) said yesterday.

Riccardo Giacconi, professor of Astronomy and specialist in x-ray astronomy, is member of the ten-man panel George B. Field, director of the CFA, said yesterday.

The chairman of the committee, sources said, is Jack P. Ruina, MIT professor of electrical engineering and computer sciences. Ruina could not be reached for comment yesterday.

A White House spokesman refused yesterday to confirm that Giacconi and Ruina were on the committee. Giacconi said this week that John Marcum, senior advisor to the president for technology and arms control, told him not to discuss the matter.

The committee met for the first time last Thursday and Friday in the Executive Office Building in Washington, D.C., and will meet again in two to three weeks, Marcum said.

A U.S. satellite monitored two bright flashes off the coast of South Africa which government scientists attributed to a low-grade nuclear explosion. After news reports of the event two weeks ago. South Africa denied setting off any nuclear explosion.

A White House spokesman said Frank Press, chief science advisor to President Carter, formed a committee of scientists to look into the matter at the president's request.

The committee, Marcum said, is concerned with three areas of investigation:

1) to see if the sighting was a false alarm due to a technical malfunction aboard the satellite;

2) to determine if some natural phenomenon "spoofed" a nuclear explosion or if some natural phenomenon interfered with the observations; and

3) to search for data which would indicate that a nuclear detonation caused the flashes "to make sure we haven't missed anything."

Richard Wilson, professor of Physics, said a State Department official phoned him on Wednesday. Wilson, who is the chairman of a Massachusetts committee now investigating the Three Mile Island nuclear power plant accident, said the evidence he has seen "seems to be fairly convincing" that the September 22 event was a nuclear explosion.

It would be difficult, if not impossible, to prove from available information that a nuclear explosion took place, he added.

Wilson said stormy conditions on the day the flashes were sighted might have dissipated the resulting radioactive fallout. The South African government said this week that it had detected no radiation from the area where the alleged explosion took place