FBI Director William H. Webster warned last night that it may be necessary for Americans to give up some privacy if the fight against crime in this country is to move forward.

Informants, electronic surveillance and undercover agents, Webster said in a speech at Georgetown University law school, are "intrusive" but he said they are "so necessary to combat high impact crime that privacy interests must yield to a reasonable degree to allow their lawful use. . . .

"We use them because they are extremely effective and often indispensable, and because we have confidence in the safeguards we have put in place," Webster said.

He said those techniques have "helped us reach beyond the criminal on the street to those responsible for some of the most serious and often hidden or protected forms of crime--organized crime, espionage, terrorism and corruption in public officials."

He said the bureau maintains tight control over informants, but he added that occasionally "when the stakes are high enough," informants may participate in non-violent criminal activity if officials have approved it.

The informant may not initiate the illegal activity, he said.

"The undercover agent is in danger of being romanticized beyond what he is in reality. He is not a panacea for law enforcement. Nor is he the threat to civil liberties that some make him out to be," Webster said.

"The voices of individual liberties and personal privacy and the voices of a society collectively demanding to be kept safe and free advance and recede with the tide. Yet both sets of voices speak of values deeply treasured by us all," the FBI director said.

A Senate committee is now examining undercover techniques in the FBI's Abscam investigation, which led to the convictions of seven members of Congress and other lower-level politicians and officials.

Webster said, "I am convinced that the FBI selectively targeted no public official and violated no constitutional safeguards."