Swiss banking authorities are examining an independent audit of Citibank's activities in Switzerland which could have implications for foreign banks operating here far beyond the possible tax violations the audit reportedly uncovered.

Earlier this week bank sources reported that Citibank might own as much as $50 million in back taxes because of questionable international currency transactions.

A well-informed source close to the case here said today that although the $50 million figure may be "exaggerated," the Swiss authorities are now investigating far more serious currency control and banking violation charges that grew out of the same audit, conducted for the bank by Peat, Marwick, Mitchell & Co.

The Board of Directors of Citibank initiated the audit by Peat, Marwick and the bank's attorneys, Shearman and Sterling, following allegations from a former bunk officer that the bank was violating tac and currency laws in several European countries.

The former employe, David Edwards, has sued the bank in New York, charging that he was fired for continually raising the allegations to higher-ups at the bank. He is asking for $14 million in damages for "wroughtful dismissal" in the civil action.

Last month, Citibank released the results of that audit. The 129 pages indicated that the bank may have violated laws in five of the seven European countries in which their branches were audited. Information from the two branches was inconclusive.

One source close to foreign banking circles here-a country considered to be a banker's paradise-worriedly said, "This is really goint to cause potential problems for foreign bankers (as) everything gets opened up."

Swiss authorities are maintaining their traditional silence concerning any banking matters, but it was learned from a Swiss National Bank official that his agency, which oversees the money supply and foreign exchange, is looking into Citibank's relationship with "the whole legal framework of capital inflow into Switzerland."

Citibank may already be in trouble for shifting funds outside the country, sources claim.

In addition, the Swiss Federal Banking Commission, the surveillence body for banking activities, is investigating theCitibank audit to see if the bank violated the declaration of good conduct which foreign banks are required to sign when they establish a branch in Switzerland..tIn Switzerland, bank sources have told The Washington Post, the Peat, Markwick auditor in Zurich who discovered probable violations-including likely back tax bills-immediately reported them to the Swiss banking authorities. The action was mandated by Swiss law.

After it learned of the probable violations, and that the potential back tax problem was raised, Citibank then approached the Swiss authorities to work out an arangement for payment of the taxes.

But the audit raised other questions, considered more serious by Swiss banking regulators.

Switzerland has, since 1971, maintained a regulatory structure primarily designed to contro the appreciation of the Swiss franc against other currencies and to inhibit the growth of the domestic money supply-actions aimed partially at curbing inflation domestically.

The resulting complex regulations place stringent restrictions and controls on lending, foreign desposits and liquidity and reporting requirements.

Swiss regulations have required, for example, that banks keep a certain percentage of their deposits from foreigners in interest-free accounts at the Swiss National Bank. This is an effort to keep foreign deposits down.

The Citibank audit indicated, however, that the bank's Zurich branch