Three more banks reported currency violations.

Michigan’s three biggest banks admitted that they “unintentionally” violated federal banking regulations requiring them to report large cash transactions. NBD Bancorp, Comerica and Michigan National said they discovered the lapses themselves in investigations begun after First National Bank of Boston in February was fined $500,000 for failure to report shipments of $1.2 billion in cash to Swiss banks. A number of other big U.S. banks have admitted failing to file the statements, and six have received sizable fines.