The mayor of Chattanooga has acknowledged that he used an encrypted smartphone app to communicate government business, according to a media report.

Andy Berke said his use of WhatsApp, which does not store messages once they are delivered, does not conflict with his administration’s commitment to transparency, the Chattanooga Times Free Press reported. Chattanooga is about 120 miles northwest of Atlanta.

“We’ve put forth a policy that says exactly what (city employees) have to do,” the mayor said. “So in most places, you could delete the next day. We don’t do that. We try to go above and beyond by putting forth a policy that says what we need to do.”

A city record and information policy adopted in December 2015 calls for the retention of chat messaging for 60 days, the paper reported.