Google is shutting down much of its social network, Google+, after user data was left exposed.
Google said that up to 500,000 users had been affected by a bug in its software, which made users’ private information accessible by third parties.
According to a report in the Wall Street Journal, the company knew about the issue in March but did not disclose it.
An internal Google memo quoted by WSJ that said doing so would draw "immediate regulatory interest".
"Our Privacy and Data Protection Office reviewed this issue, looking at the type of data involved, whether we could accurately identify the users to inform, whether there was any evidence of misuse, and whether there were any actions a developer or user could take in response,” the firm said in a statement. "None of these thresholds were met here."
Google said it would continue to offer private Google+ powered networks for businesses currently using the software.
"It has not achieved broad consumer or developer adoption, and has seen limited user interaction with apps," wrote Ben Smith, Google's vice president of engineering, in a blog post on Monday.
Shares in Google's parent company Alphabet fell by 1.23 per cent.