A Russian internet company said it has received complaints that its search engine turned up some Google documents that appeared to be meant for personal use.
Yandex spokesman Ilya Grabovsky said some users contacted the company to say that its public search engine was yielding what looked like personal Google files.
Mr Grabovsky said the company has alerted Google.
It is unclear whether the files were meant to be publicly viewable by their authors or how many there were.
On Wednesday night, Russian social media users started posting scores of documents they said turned up in the search.
Mr Grabovsky said that a Yandex search only yields files that do not require logins or passwords. He added that the files were also turning up in other search engines.