President Carter has asked attorney Charles H. Kirbo, his closest friend and unofficial adviser, to monitor the current investigations of the General Services Administration, The Washington Post has learned.

"The president has asked Mr. Kirbo to help monitor and observe the GSA investigations," Rex Granum, deputy White House press secretary said when asked yesterday about Kirbo's role. "He will be advising the president on it, indicating the importance the president places on the matter."

Kirbo "will be talking to Justice people as warranted," Granum said, " and presumably will be receiving information from Justice on the investigations."

Reached at his home in Atlanta last night, Kirbo said he already has talked with Attorney General Griffin Bell and other Justice Department offficials about the several ongoing Federal investigations of GSA corruption. He also said he has conferred with GSA Administrator Jay Solomon.

"When there's something that's important to (President Carter), and he has a lot of other things to do, I just take a look at things and advise him," said Kirbo, a lawyer in private practice in Atlanta.

Sources said yesterday that federal prosecutors in Washington and Baltimore, who are directing the two major grand jury investigations of GSA, have not been informed of Kirbo's role.

Justice Department officials, according to the sources, questioned the propriety of a private citizen monitoring federal investigations in this way. One official noted that federal law prohibits divulgence of grand jury testimony to anyone not involved in prosecuting the cases under investigation. "We could not give such information to Mr. Kirbo," the official said.

Kirbo said last night, however, that "there's no problem." Asked if he would be receiving information from grand jury testimony, Kirbo said, "I don't want to know anything about that."

Another Justice Department official wondered whether Kirbo's assignment is an indication that President Carter questions the ability of the Justice Department to handle the GSA cases and report on their progress.

Asked about this yesterday, Granum at the White House said, "The president very much trusts (Kirbo's judgment to give advice on it."

A spokesman for Attorney General Bell said Bell has quite a different view of Kirbo's function. "The attorney general's understanding is that Mr. Kirbo has been asked to counsel (GSA administrator) Jay Solomon on whatever needs to be done at GSA," said Terrence B. Adamson, a special assistant to Bell.

Although Kirbo frequently talks with Bell on a range of matters, Adamson said, "This (Kirbo's new assignment) has nothing to do with Justice."

Carter asked Kirbo to assume his new role Monday after Carter discussed the GSA investigations at the White House with Solomon and Deputy Attorney General Benjamin R. Civiletti, who heads Justice's criminal division. Carter told Civiletti on Monday he wants "bigger fish" involved in the GSA scandal prosecuted.

Carter called the surprise meetings with Civiletti and Kirbo, according to a source, after he read in Sunday's Washington Post that one GSA official under investigation had said he thought that, under political pressure, Carter might pardon GSA officials who broke the law.

After being contacted by the president on Monday, Kirbo met Wednesday with GSA Administrator Solomon and GSA special counsel Vincent R. Alto to inform Solomon that he would advise him and report to Carter about any assistance Solomon might need in cleaning up GSA.

Solomon is known to have complained to aides that he has not been able to see the president as often as he would like to discuss the GSA scandal, which Alto has called the biggest in terms of money in U.S. history.

Kirbo, according to sources, also asked Solomon on Wednesday if he was receiving sufficient cooperation from the Justice Department and Attorney General Bell. Solomon assured Kirbo that he was, the sources said.

Over the past month, however, Solomon and Alto have told Bell and Civiletti they did not feel that the GSA investigations in Washington have been pursued as aggressively as they could be. Prosecutors and FBI agents here have countered that GSA has not been fully cooperating with them.

Sen. Lawton Chiles (D-Fla.), chairman of the Senate governmental affairs' federal spending practices subcommittee, complained yesterday that some federal investigators have spent "more time fighting among themselves than conducting criminal investigations."

"As public interest in the GSA scandals rises, the race for glory becomes more intense," said Chiles, who held hearings in June on GSA corruption and waste and is expected to convene additional hearings this month.

"My investigators report that several rapidly progressing and very promissing investigations have become bogged down in a three-sided name-calling contest among FBI agents, GSA investigators, and Justice Department personnel," Chiles said.

Chiles said he has asked Civiletti and Alto to meet with him next week to try to reach an agreement that might reduce yhe friction. Barring that, Chiles threatened to publicize the names of federal officials who continue to investigate each other rather than potential criminals.

Federal investigators in Washington have established that GSA managers of many federal buildings here have accepted bribes in return for approving GSA payments to building maintenance and repair firms for work never done.

In Baltimore, prosecutors have evidence that managers of 27 GSA supply stores that provide office supplies to federal workers in Washington and its region have accepted cash and gifts in return for approving GSA payments to suppliers for merchandise never delivered.

GSA Administrator Solomon recently announced that these investigations are expected to produce indictments against at least 50 GSA employes, repair and maintenance firms, and office-supply companies. Investigations into similar abuses in other GSA regions have been started by prosecutors in cities across the country.

Stories published in The Washington Post in recent months have detailed how GSA, which provides offices and supplies for federal agencies, has lost millions of dollars through the way it buys office equipment and furniture, constructs federal buildings, leases building from private landlords and sells stockpiles of unused strategic materials.

The Post reported Wednesday that Jack M. Eckerd, Solomon's predecessor as head of GSA, seemed disinterested and took no action when told by a consultant that GSA was losing $1.3 million a year through thefts of equipment and supplies from its warehouses around the country.

Eckerd, who is one of two Republican candidates for governor of Florida, charged he had been falsely accused of poorly managing GSA because he had "stepped on the toes" of powerful political figures such as House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.).

Eckerd said that the consultant's study contained errors that doubled the amount of theft found. He also disputed the consultant's claim that Eckerd appeared "hostile" to the findings.

"The power structure as exemplified by Tip O'Neill is definitely involved," Eckered said. "The speaker turned purple when I resigned (from GSA) rather than accept his Boston crony (Robert T. Griffin) as my assistant . . . Friends warned me at the time that Tip O'Neill would try to get even."