More than $100 million of excess funds amassed by the United Nations and its affiliates is being kept in U.S. and foreign bank accounts that pay little or no interest, audited financial statements show.

The U.N. system thus would appear to be forfeiting millions of dollars it might collect each year in interest at a time when it is complaining of deficits and difficulties in collecting assessments from member countries.

The United Nations Children's Fund (UNICEF), one of the organizations that make up what is known as the U.N. system, keeps an average of $10 million in interest-free checking accounts.

The United Nations itself, along with the United Nations Development Program (UNDP), keeps an average of $20 million in interest-free checking accounts.

At current interest rates of more than 9 percent for overnight investment of large funds, these sums along represent a loss of interest of nearly $3 million a year.

In addition, at the end of 1977, U.N. system organizations had these amounts in banks:

More than $11 million of the United Nations Fund for Population Activities (UNFPA) earning interest of 1.75 percent a year in Japanese banks.

More than $17 million of the United Nations Educational, Scientific and Cultural Organization (UNESCO) in various accounts paying little or no interest.

More than $24 million of the UNDP in Japanese banks earning interest of 3.25 percent a year.

More than $2 million of the UNDP funds in Netherlands banks earning interest of 1.5 percent a year.

More than $7 million of the United Nations' funds in a 5 percent savings account in Chemical Bank in New York.

More than $4 million of UNDP money in a 5 percent savings account.

More than $1 million of United Nations University funds in a 5 percent savings account at Chemical Bank in New York.

The deposits are part of $1.4 billion in excess funds kept by U.N. system organizations in various bank accounts throughout the world. A story in The Washington Post yesterday reported that U.N. organizations have been amassing a surplus of as much as$350 million a year.

Officials of UNICEF and other U.N. organizations said much of their interest-free money is in hundreds of accounts in foreign countries where it may be difficult to transfer money readily or obtain interest on deposits.

They said savings accounts may be used to hold money temporarily until it is needed to cover checks. On other deposits, they said, they obtain quotes from several banks to get the best interest rates.

While interest rates at some foreign banks may seem low, they said, the deposits may bring a higher rate of return than if the money were invested in the United States because of foreign exchange fluctuations.

U.N. organizations declined to allow access to records that would show the full terms of their deposits. "Unless you have the logic behind the transaction, you could not form a rational opinion on it," G. Arthur Brown, deputy administrator of the UNDP, said in declining to make available UNDP banking records.

Giovanni Cavaglia, comptroller of UNICEF, said disclosing interest rates on the organization's bank deposits of more than $100 million would give a competitive advantage to banks that bid for UNICEF's business.

The United Nation's board of auditors, which has access to the banking records, has criticized the way the United Nations manages its excess cash.

Referring to the hundreds of millions of dollars available for investment, the board, composed of auditing staffs from three countries, has called for forecasting cash needs based on when checks are presented for payment, closer monitoring of cash needs in overseas accounts, and integrated system for investing funds from all U.N. offices.

Asked why the UNDP was earning interest of only 3.25 percent a year on deposits of more than $24 million in Japan, Deputy Administrator Brown said Japan is one of the countries that imposes restrictions on money it contributes to the or organization.

"Seven or eight countries (including Japan) require us to keep money until needed in their countries and designated the bankss where it will be held," Brown said. "The rate is set by the bank."

Brown said he did not believe the UNDP got a lower rate in Japan as a result. But data published by the International Monetary Fund, which tracks foreign money transactions, show that overnight bank deposits of as little as $100,000 were earning annual interest in Japan at the time of more than 5 percent.

Asked what it recommended for overnight investment $1 million, American Security Bank, one of Washington's major banks, said it offers a return of 9.9 percent a year through purchases of government securities.

G. Peter Wilson, director-general of the U.N. external audit committee, said the auditors are concerned about the United Nations' cash managment practices.

"When we see a lot of (excess) money, we ask if it is adequately protected and invested in the best manner," he said, "What we haave found is they (the U.N.) don't have systems for doing that adequately. There isn't much incentive for not leaving the money uninvested." CAPTION: Illustration, Money in the Bank, The Washington Post