Citibank, the nation's largest, has made back-tax and penalty payments to Switzerland and France totaling nearly $6.9 million as a result of questionable foreign currency transactions made by the bank's branches in those countries during the mid-1970s, the bank said yesterday.

Furthermore, the bank will pay another $3.7 million to another European country that sources said was West Germany. A Citibank spokesman said the payment was related to "normal tax disputes" between multinational companies and governments and was not due to questionable foreign exchange practices.

The revelations came in a new study of the controversial foreign exchange transactions that was prepared by the directors of the bank's parent company, Citicorp. A more exhaustive study in 1978, triggered by allegations of a bank employe in Paris, said that while the bank may have engaged in some foreign exchange transactions designed to evade taxes, there was no overall pattern of such transactions nor did they represent bank policy.

The report released yesterday identified 26 questionable foreign exchange transactions in which bank branches sold currencies in order to generate losses in the two high-tax European countries and similar profits at the Citibank branch in low-tax Nassau.

The bank said that all but $1.2 million of the payments, including the one to West Germany, can be credited against U.S. taxes.

Both the Comptroller of the Currency and the Securities and Exchange Commission, after lengthy investigation, declined to take any actions against Citicorp. The SEC staff recommended that the commission censure Citicorp, but the commissioners disagreed.

Darwin E. Smith, chairman of Citicorp's audit committee as well as chairman and chief executive of the Kimberly-Clark Corp., said last April that the board would reopen the investigation because of a suit filed by a shareholder on behalf of the company, demanding that damages be sought from 15 current and former Citicorp executives.

In such actions, called derivative suits, a company's directors are supposed to decide whether the suit is wise.

The seven-member audit committee, composed of directors who are not employes of Citicorp, said the suit should be dismissed because it found that none of the defendants, including Citicorp chairman Walter Wriston, knew anything about the questionable foreign exchange trades. None of the audit committee members are defendants in the suit, filed by Harry Lewis, who owns 12 shares of Citicorp stock. In addition, the audit committee report said, the amount of damages that might be recoverable would be more than eaten up by legal expenses.

The audit committee reported the bank's Zurich branch in 1974 made two separate transactions -- one in April, one in May -- that resulted in $7.5 million in losses on the Zurich books and $7.5 million in profit on the books of Citibank's branch in Nassau. Taxes in Nassau are lower than in Zurich.

Citibank has paid $5.7 million in tax settlements to Switzerland and the Canton of Zurich.

Citibank also paid more than $1.1 million in tax and customs settlements "related solely" to a series of 24 foreign exchange transactions in France. The report called the transactions "quite complex" and said they involved the Paris and Nassau branches of Citibank, the New York office and an unaffiliated, unidentified London bank.