SAN FRANCISCO — The chief of Uber Tuesday gave details of the theft of personal information of 57 million customers after the US ride-hailing giant this week fired its chief security officer for concealing the data breach.

Uber CEO Dara Khosrowshahi acknowledged in a blog post on the company's official website on Tuesday that a year ago two hackers broke into a third-party cloud-based system that contained the private information of its customers.

Though he said there was no evidence to show that key personal information such as the customers' credit card, bank account and social security numbers had been stolen and abused, he admitted that other sensitive data had been illegally downloaded.

Such information included names, email addresses and mobile phone numbers of 57 million Uber users around the world, and the names and license numbers of 600,000 drivers.

"We have to be honest and transparent as we work to repair our past mistakes," Khosrowshahi said. "None of this should have happened, and I will not make excuses for it."

"While we have not seen evidence of fraud or misuse tied to the incident, we are monitoring the affected accounts and have flagged them for additional fraud protection," he added.

He said his company is notifying the regulatory authorities about the theft for possible further investigation.

This week Uber fired its chief security officer Joe Sullivan, along with one of his subordinates.