The Russian Internet company Yandex said in a statement that some users contacted the company Wednesday to say that its public search engine was yielding what looked like personal Google Documents files, suggesting there may have been a data breach.
On Wednesday night, Russian social media users started posting scores of such documents, including an internal memo from a Russian bank, press summaries and company business plans. The veracity of those documents could not be independently confirmed.
Google said in a statement that search engines can only turn up Google documents that had either been deliberately made public by its authors or when a user publishes a link to a document and makes it available for public access and search.
"Saving and protecting users' personal data is our main priority," the company said. "Google Documents is a highly protected tool for joint work and it is working correctly."
It did not elaborate.
Ilya Grabovsky, a spokesman for Yandex, said its search only yields files that don't require logins or passwords. He added that the files were also turning up in other search engines.