Twitter has apologized to its users for abusing their phone numbers and email addresses.

The internet giant claims that they "inadvertently" used the data for advertising, although they asked for account holders as a security measure.

Numbers and addresses were requested by Twitter registrants to prove the authenticity of the accounts. They were then provided for comparison with the lists of numbers and addresses used by the sales department to send targeted ads to the Internet.

"It was a mistake and we apologize. We will take steps to prevent this from happening again," they wrote on Twitter.

According to the San Francisco-based company, the issue was resolved in mid-September, and user data did not leave Twitter servers.

Internet data privacy is a hot topic and topic of debate around the world, and giants such as Twitter and Facebook have been closely monitored by regulators in different countries.