Weak controls over U.S. aid have allowed foreign governments to spend billions of dollars without proper accounting and to divert funds to officials' families and pet projects, newly released documents show.

Federal investigators disclosed in interviews last week that they had recently uncovered misuse of U.S. economic aid in Egypt, Thailand, Kenya and Costa Rica.Egypt, which receives the second biggest share of U.S. aid, has in recent years deposited $1.5 billion of assistance in accounts containing other budget funds - making it impossible to trace how the American money was used, an audit by the Agency for International Development inspector general's office found.

The June 1987 audit, obtained by United Press International under the Freedom of Information Act, said AID had allowed Egypt to keep $325 million of assistance sitting idle, collecting no interest, in the Central Bank of Cairo.

AID spokesman Bart Kull said the agency has just put into effect auditors' recommendations aimed at improving oversight of U.S. assistance. The Egyptian embassy had no immediate comment.

In Costa Rica, the daughter of Carlos Gutierrez, the former foreign minister who now serves as Costa Rican ambassador to the U.N., received a scholarship worth several thousand dollars for harp training at the Cleveland Institute of Music, AID Inspector General Herbert Beckington said in an interview.

For more than a year, AID has been trying to decide whether to discipline Dan Chaij, its Costa Rican mission chief, for allowing half a million dollars in U.S. scholarship aid to Gutierrez and other "socially advantaged," a former administration official said.

Beckington told UPI that the Costa Rican government made no attempt to discipline its officials or recover the funds. AID and the Costa Rican embassy had no comment.

Beckington said the widespread lack of accountability and occasional corruption in aid programs undoubtedly have limited their effectiveness.

"We have no idea what's happening to many of our funds," he said. "AID has one of the most severe management and control problems of any U.S. agency."

Rep. Henry Hyde, R-Ill., who introduced a bill last year requiring closer program oversight, said of the audit findings: "This is absolutely outrageous. I believe in foreign aid, but we can't keep shoveling it out without seeing where it lands."

The administration has resisted congressional efforts to tighten restrictions on the use of economic aid, arguing that allies who help advance U.S. foreign policy goals should be allowed flexibility in their use of assistance.