Google says it has disabled an iPhone app that it had paid some users to install to study their digital habits, following a similar move late on Tuesday by social media network Facebook.
Google and Facebook had faced criticism from privacy experts for distributing their research apps through a programme iPhone maker Apple had created for companies to distribute apps to employees.
"The Screenwise Meter iOS app should not have operated under Apple’s developer enterprise programme — this was a mistake, and we apologise," Google said in a statement.
Apple did not immediately respond to a request to comment.
Reporting by Paresh Dave. Editing by Bill Rigby