The head of the American Medical Association told the president's AIDS commission yesterday that the AMA opposes widespread mandatory testing for the virus because it would yield too many false positive results and would not be a good allocation of medical resources.

"We run into a real problem of false positives and the possibility of destroying someone's life," said Alan R. Nelson, the Salt Lake City internist who is chairman of the AMA.

His remark was in response to commission member Cory Servaas, who is a physician and publisher of The Saturday Evening Post. She asked why the nation's doctors were not testing all patients at no charge and why the AMA was not pushing such an approach.

Disputing Nelson's contention that false positives would be a major problem in any widescale testing of low-risk populations, Servaas cited the Defense Department testing program, which she said has an extremely low false-positive rate.

However, the officials who run the Pentagon program have told congressional committees that they achieve their high accuracy rate only by strictly monitoring the procedures used by the laboratories that the Defense Department pays to do the testing. Nelson noted that a number of studies have shown that the accuracy rate of the scores of private labs performing AIDS tests, which are not subject to government oversight, varies widely.

Kristine M. Gebbie, head of Oregon's State Health Division and a new member of the commission, stepped into the exchange between Servaas and Nelson to say commission members should exercise care to avoid giving misleading information during commission meetings.

When Servaas persisted and denied that she was putting out misleading information, Gebbie shot back, "Your question is misleading. And that's my point."

Later in the hearing, Servaas sought volunteers to go with her to New York to ask magazine publishers to print surveys on how the American public is dealing with AIDS and what the public wants done in such areas as sex education.

No members volunteered to help her. Commission Chairman James D. Watkins said the panel would take the matter under advisement for "internal" discussions.

Watkins made clear that the panel's Dec. 7 interim report, rather than making recommendations, will be little more than a progress report on what the panel has done. Its final report is due June 24.