Representatives of mutual funds charged leaders of the banking and savings and loan industries yesterday with trying to stifle competition through their joint effort to restrict the growth of money market funds.

The Investment Company Institute, the mutual fund trade association, asked the Justice Department to investigate the change, claiming that leaders of those industries are effectively price-fixing by attempting to limit the activities of money market mutual funds.

"It is outrageous that some 90 years after the enactment of the first antitrust law, a banking group or combinations of banking and savings and loan groups would arrogate to themsleves the right to dictate to the American public the returns on their savings by curtailing competition," the institute wrote in a letter to Sanford M. Litvack, head of the Justice Deparment's antitrust division.

The letter, sent yesterday by the institutes' general counsel Matthew P. Fink, comes just three days after top officials of the American Bankers Association and the United States League of Savings Associations announced they would discuss possible joint efforts to develop legislation and other programs to slow the exodus of savings funds to money market mutual funds.

The banking and savings and loan officials are disturbed because money market funds operate without regulatory ceilings on the interrest rates they can pay savers.

Leaders of the two associations regularly disagree about key financial industry issues. But both are plagued by enormous growth of the money market funds, which can offer about three times the interest rate of passbook savings accounts.

Government regulators and members of Congress have said recently that there is little need to step up regulation of these money market funds, and key federal regulators have praised the establishment of these instruments.

The letter from the Investment Company Institute pointed out that the group "has no real quarrel" with the efforts of bankers to lift restrictions, such as Regulation Q, that limit their ability to raise interest rates.

"What does disturb us is a combination of bankers and savings and loan officials seeking to procure repressive regulation and legislation for the sole purpose of damaging competitors," Fink wrote in the letter to Litvack.

"We believe that such blatantly anti-competitive activities designed to reduce competition and, indeed, to engage in a species of price-fixing by determining the returns that savers may earn on their money, warrants at least a preliminary review to determine the lawfulness of such activity."

Fink asked the Justice Department to "give some priority to examiing the issues" raised by the "formation of a consortium of supposedly competing industries to embark on a program of anti-competitive harassment of money market mutual funds to the detriment of the three million shareholders of these funds."

On Monday at a conference on the banking industry sponsored by Virginia Commonwealth University, C. C. Hope Jr., president of the ABA, and Edwin B. Brooks, president of the U.S. League, announced that the talks on the joint effort began last week.