The General Accounting Office urged Congress Monday to examine carefully the risks U.S. banks incur through more liberal securities activities overseas than are allowed in the United States.

The GAO, in testimony and in a report to Congress, told a House Banking subcommittee that "perhaps, for competitive reasons, we have to apply different standards to banks' securities activities in U.S. and foreign markets. But the potential risks associated with applying different standards need to be looked at very carefully."The GAO noted that "we see no reason to assume that securities activities in foreign markets are any less risky than in domestic markets."

The Federal Reserve Board in September 1989 voted to allow non-banking subsidiaries of bank holding companies to engage in underwriting and selling of all types of securities, provided that revenue from those sales does not exceed 10 percent of the subsidiary's total revenues.

Fed Vice Chairman Manuel Johnson told the subcommittee in prepared testimony that securities activities of U.S. banks overseas are also constrained by other nations' laws. He said that those banks cannot deal in any more than $15 million of securities of any one issuer's securities.

However, Mr. Johnson said the Fed board was investigating whether it could apply its same 10 percent revenue-limit rule to the securities arms of U.S. banks operating overseas.

The GAO noted that under the Fed's revenue limits, the subsidiaries of 13 bank holding companies underwrote a total of about $69 billion of newly authorized securities during the third quarter of 1989.

The GAO noted that almost all of this was in commercial paper but said it was "too early" to know the potential risks to banking firms from this third-quarter activity, or about the long-term effectiveness of Fed regulations in limiting the risk to these firms.