Yahoo has launched a new service called Yahoo Account Key, which allows users to use their smartphones for identity verification instead of passwords, making way for password free logging in.

The password-free method of logging in completes what Yahoo had started with its SMS-based two-factor authentication in March.

Unlike the two-factor authentication, which was launched as a secondary back-up measure for account authorisation, the Account Key works as a primary access for the mailbox.

Yahoo product management vice president Dylan Casey said: "Passwords are difficult to remember and secondary sign-in verification is inconvenient and confusing.

"Earlier this year we launched on-demand passwords using an SMS code.

"We’re now taking a major leap towards a password-free future with the launch of Yahoo Account Key, which uses push notifications to give users simple and secure access using their mobile device."

The service works when users with Account Key try to access their Yahoo Mail, not needing to enter their conventionally used passwords.

It will forward a message to the smartphone or tablet connected with the account asking whether it is a legitimate attempt for logging in.

Users can deny unauthorised access, and will need to verify identities through an email or a text message sent to alternative accounts and numbers in case their device is lost or stolen.

The search major has launched their service in connection with their new mailbox app which offers multiple mailbox support along with smarter search, contacts management and rich compose.

The password-free service will be rolled out later across its other applications as well.

Apart from Gmail, the new Yahoo Mail app allows users to connect their mail accounts from Outlook.com, Hotmail, and AOL, and will be available on iOS (iPhone and iPad) and Android platforms.