Google has issued a warning to millions of Google Chrome users whose browsers may be infected.

The tech giant is alerting users to the serious problem, which could see them targeted by criminals, and advising people of the five warning signs to look out for.

If your browser is infected you could be targeted with spam ads, spied on, or have your personal information stolen.

Google said: “If you're seeing some of these problems with Chrome, you might have unwanted software or malware installed on your computer.”

Your browsers may be infected if you start seeing pop-up ads or new tabs that won’t go away.

The Northern Echo:

The second warning sign, according to Google, is that your homepage or default search engine may start changing without your permission, while a third warning sign is If unwanted Chrome extensions or toolbars start appearing.

You may also see alerts about a virus or an infected device, or you may find that your browsing experience is hijacked and you are redirected to unfamiliar websites or adverts.

If you experience any of those issues, you should take action to protect your browser.

This can be done by launching Chrome and going into settings in the top right of the screen.

From there, select Reset Settings > Restore Settings To Their Original Defaults > Reset Settings.

Google explained: “If you reset your browser settings, you might need to turn some extensions back on.

"To turn extensions on, at the top right, click More More and then More Tools and then Extensions. Only turn on extensions you trust."

A further warning from Google said: “Watch out for things that look too good to be true.

"Winning a contest or getting expensive copyrighted content at no charge is sometimes a trick to get you to download malware.

"If you haven't recently run a virus scanner, be wary of warnings about viruses or infected devices.

"The site might be trying to scare you into downloading unwanted software.

"Only download files or visit sites that you know are secure."