June 17 (Reuters) - Cruise operator Carnival Corp detected unauthorized access to its computer systems in March, alerted regulators and hired a cybersecurity firm to investigate the breach, Bloomberg News reported on Thursday. Carnival, whose shares were down 2%, noticed the suspicious activity on March 19 and acted quickly to "prevent further unauthorized access," the report added. (bit.ly/3wAmnjz) The Miami-based company also alerted individuals whose data had been compromised and set up a call center to respond to their queries, according to the report. Carnival did not immediately respond to a Reuters request for comment. The company was also hit by a ransomware attack last year, which affected the information technology systems of one of its brands. Reporting by Niket Nishant in Bengaluru Our Standards: The Thomson Reuters Trust Principles.