Twitter has issued a statement apologizing for unintentionally using contact of users, emails and phone numbers, to enable target advertising. The company said that they are unable to say how many people have been affected.

The company added in the statement that a third-party marketers might have reached Twitter users based on contact details. They added that the issue was fixed as of September.

“As of September 17, we have addressed the issue that allowed this to occur and are no longer using phone numbers or email addresses collected for safety or security purposes for advertising,” said the statement.

The statement added “When an advertiser uploaded their marketing list, we may have matched people on Twitter to their list based on the email or phone number the Twitter account holder provided for safety and security purposes. This was an error and we apologize.”