Google has warned users to improve the security of their accounts after billions of website passwords have been hacked.

Axar.az reports citing Birmingham Live, hundreds of thousands of usernames and password combinations are at risk, the search giant confirmed.

At-risk users are being warned that they have "one of over four billion usernames and passwords" that have been hacked.

As a result of the hacking, Google has released a "how-to" guide to help users with their account security and make passwords stronger, which includes installing the Password Checkup add-on for Google Chrome which was launched last year.