The government in the last few days has won the cooperation in its Pentagon bribery probe of someone whose voice turned up frequently on court-ordered wiretaps, a source familiar with the matter said Tuesday.

A second target of the probe appears on the verge of cooperating, said the source, who demanded anonymity.It could not be determined whether the target who is cooperating is a Pentagon employee, a consultant or a defense contractor.

Sources familiar with the probe also said that one wiretap involves a conversation between former Navy Secretary John Lehman Jr. and his then-aide Melvyn Paisley.

The sources said that conversation, recorded late last year or early this year, can be interpreted as being a tip-off by Lehman that Paisley might be under investigation.

Attorney General Edwin Meese III refused to say Monday whether Lehman is among those under scrutiny. Paisley and another former Lehman aide, retired Adm. James A. "Ace" Lyons, have been implicated.

The sources, speaking on condition of anonymity, refused to describe the possible warning, which investigators are examining as a potential obstruction of justice and which occurred after both Lehman and Paisley had left the government.

The government frequently relies on gaining the cooperation of participants in a white-collar conspiracy to win the conviction of bigger targets.

Meanwhile, Defense Secretary Frank C. Carlucci is reassigning five Pentagon officials under scrutiny in the Pentagon bribery probe, other sources said.

Those sources, who spoke only on condition they not be identified, said Carlucci had signed an order directing the reassignments. The sources said the affected employees were being notified of the decision by their respective services Tuesday.

The five are:

-James Gaines, the deputy assistant Navy secretary for acquisition management.

-Dr. Victor Cohen, the deputy assistant Air Force secretary in charge of buying tactical command, control, communications and computer systems. His office was searched last week.

-George Stone, a Navy official in the Space and Naval Warfare Systems Command.

-Stuart Berlin, an executive with the Naval Air Systems Command.

-Marine Corps official Jack Sherman, who works in the equipment and service acquisition section of the contracts division, installation and logistics department.

One source called the reassignments "a dicey thing."

"They haven't been charged or indicted, and most of them are civil service."

The action followed a high-level meeting on Monday at which Pentagon officials reportedly studied what actions they could take in the case.

Carlucci may also consider whether to suspend contracts with the companies involved in the probe, including some of the biggest military suppliers in the country.

The companies' offices were searched last week in pursuit of illicitly obtained inside contracting information.

Suspension of contracts could be disruptive to the military, ruinous for contractors who live or die on government business, and damaging to their employees.