The heads of the two most secretive U.S. agencies said yesterday that more should be done to fill what a Senate report calls a "vacuum" in government handling of Soviet-bloc defectors.

William H. Webster, director of central intelligence, said his agency had assigned more experienced officers to handle defectors from the Soviet KGB and its allied spy agencies after the highly publicized "redefection" of Vitaly Yurchenko in November 1985.

"There has been a substantial increase in the number of intelligence officers assigned to this work and a shift in emphasis," Webster said in his first public testimony before Congress since becoming head of the Central Intelligence Agency.

Webster and Lt. Gen. William E. Odom, head of the National Security Agency, said much more could be done to use the experience of Soviet-bloc defectors not of immediate interest to U.S. intelligence.

Odom, whose agency intercepts and deciphers electronic communications of other nations, described two Army programs to harness Soviet defectors' skills for study of the Red Army. Senate investigators have also pointed to those programs as models of how to tap the defectors' unique insights.

Those programs offer jobs to a limited number of defectors and help them adapt to free societies of the West.

But, in many cases, Odom told the Senate Governmental Affairs permanent subcommittee on investigations, he has perceived "a genuine hostility to the views of these emigres. Many American scholars have a much more benign view of the U.S.S.R. than do most emigres," he said.

Webster and Odom, who almost never appears in public, testified as the subcommittee released a report finding that the government often ignores senior officials who have fled communist societies.

Some are never questioned by U.S. officials, and others languish for years performing odd jobs, the report said.

"We must better learn how to assist and utilize the genuine defector, who usually arrives at our doorstep in his flight for freedom with nothing more than the shirt on his back," said subcommittee Chairman Sam Nunn (D-Ga.), who ordered the probe.

Investigators interviewed Webster and Odom and concluded that "a vacuum exists in current government programs for the systematic identification and productive integration of a significant group of defectors into U.S. public life."

The government, the report said, should find more ways to use and to aid Soviet-bloc defectors whose experience as diplomats, economists, scientists or soldiers could give key insights into communist systems. "The staff found that defectors are not 'squeezed like a lemon and thrown away,' as commonly alleged in the Soviet press," the report said. "Instead, most defectors seem to wish they had been 'squeezed' a little more."

It said "much more could be done to better utilize and assist" defectors who were not Soviet-bloc spies and thus not of immediate interest to U.S. intelligence.

Among the most striking examples of such neglect, it said, were:

Tadeusz Kucharski, who defected in 1983 after serving five years as Polish commercial attache in Angola and "was never even debriefed . . . concerning Soviet and Polish activities" there.

Petre Nicolae, a high-ranking Romanian government economist, who "spent over five years in New York running a laundromat and selling ice cream."

Vladimir Sakharov, a Soviet diplomat who, after defecting in 1971, was advised by a U.S. government official to become a motel manager.

Andrei Sorokun, a KGB recruit proficient in English and Japanese, who was never questioned by U.S. officials.

Alexandra Costa, first successful defector from the Soviet Embassy here since World War II, who was advised by CIA handlers to work as a secretary.