The Voice of America, in an unusual broadcast yesterday, aired an interview with Secretary of Defense Caspar W. Weinberger followed by a Pentagon clarification of what he said.

Weinberger, the guest Sept. 16 on the VOA-sponsored program, Press Conference USA, was questioned about U.S. allegations that the Soviet Union may be involved in chemical-biological warfare in Cambodia.

His answers seemed to imply that the United States might be considering either revising treaties banning such warfare or developing an ability to "respond in kind" as a way to deter Moscow.

Weinberger's lengthy answers appeared to surprise or confuse the reporters who questioned him. They repeatedly returned to the subject.

At one point, Weinberger said: ". . . One of the things we have to do is to make sure we have some kind of balancing forces and indeed are embarked upon the necessity, embarked upon the course that will redress this imbalance . . . ."

At another point, he said, ". . . possibly a knowledge that the Soviets face retaliation in kind might be a deterrent that would prevent these things from ever having to be used."

The United States cannot allow one power to accumulate "mass quantities of weapons without any kind of counter-balancing deterrent," he said.

The program was to have been broadcast last Saturday. A VOA spokesman said it was delayed at the Pentagon's request because the Pentagon thought Weinberger's remarks would "anticipate" a United Nations debate that may take place this week on the U.S. charges.

It is known, however, that Weinberger's remarks also caused a stir within the State Department concerning what the defense chief said, not just when he said it. Asked if anything else would accompany the broadcast, aired over VOA's worldwide English language service, the VOA spokesman said the following announcement would be included:

"Since this program was recorded last week, the Defense Department has requested that the following clarification, which the secretary made to members of the panel following the program, be appended to this broadcast:

"The U.S. policy regarding biological warfare is very clear. We have renounced any use of biological and toxin weapons and remain in full compliance with the biological weapons convention.

"Secretary Weinberger refers in several instances to deterrence or retaliation in kind. In these cases, he means redressing the imbalance through the development of an adequate protective posture and the development of a modernization program for chemical weapons, the construction of the first phase of which has been approved by the president and supported by Congress."