"Credit Suisse has provided information about US customers" to US authorities, the bank's Chairman of the Board of Directors Urs Rohner said in an interview in the Swiss weekly NZZ am Sonntag.
Although he would not say which type of data was transferred, on Saturday evening Swiss Minister of Finance Eveline Widmer-Schlumpf said the bank had provided "statistical data" to US authorities.
"But there was no personal data ... that would be a violation of banking secrecy," she said on national television.
Credit Suisse, like other Swiss banks, is under pressure from US authorities investigating tax evasion.
Swiss media have been reporting this week that Washington had given Credit Suisse until Tuesday to provide information on US nationals who might have improperly hidden money in Switzerland.
"Today, no one questions that American customers had undeclared assets in Swiss banks," Rohner said in the interview.
The question, he said, was whether there had been a violation of US law.
"For us ... it has always been clear that the rules and regulations of foreign countries have to be respected," Roehner said.
Credit Suisse employees who did not follow these rules, he said, "will be sanctioned".
"Our business model is not based on undeclared money," he added.