Twitter has apologised for "unintentionally" using email addresses and phone numbers, provided by users for account security, to enable targeted advertising.

The company said third-party marketers may have been able to reach specific users on Twitter based on contact details, even if the user had not wished the information be used this way.

In a statement, Twitter said it "cannot say with certainty how many people were impacted", but the BBC understands it affects users globally. Read on: