Twitter on Wednesday unveiled technology to boost security for its users. The popular network has begun rolling out an optional "login verification" service to thwart hackers seeking to hijack accounts with stolen passwords. When users log in to Twitter via a web browser, they must confirm their identity by entering a six-digit code that Twitter delivers to their smartphones. To access the service through applications for PCs and smartphones, users must use an automatically generated temporary password for each of the programs.

The move is following a number of attacks on accounts of prominent media outlets including the Associated Press, the Financial Times and The Onion.

Microsoft, Google and Facebook already allow two-step verification as an option.