User of the popular Whatsapp messenger have been advised to watch out for a scam which tries to charge them for using the free service.

Many users across the world have reported receiving fake text messages warning them that their subscription has run out.

The message contains instructions on how to receive a lifetime subscription for a small sum of money and is being sent by scammers trying to trick users into sending their payment details.

The scam first appeared at the beginning of May.

Read more: Anti-piracy group shuts down THREE popular Kodi repos and add-ons

The message reads: "Your subscription has expired. To Verify your account and purchase a lifetime subscription for just 0.99 GBP simply tap on this link".

Whatsapp did initially charge users 99p after the first year of use when it first launched in 2010, but this was soon scrapped.

People who have received the message should delete it immediately.

If you have clicked on the link within the message, you should run antivirus software to ensure your device has not been infected with malware.    

Read more: Anti-piracy group shuts down THREE popular Kodi repos and add-ons

You can also block the sender, so they can no longer message or call you through WhatsApp.

To block a number that isn’t saved to your phone, open the WhatsApp conversation and hit Block. You can also report the user as Spam.

If you’ve received a spam message from one of your contacts, you can block them by tapping the menu button on the WhatsApp home screen, selecting Settings > Account > Privacy > Blocked contacts, and adding that contact to your Blocked list.

It is unknown how many users have been targeted or how the scammers obtained the phone numbers.