Money Saving Expert founder Martin Lewis has issued an urgent warning to anyone with a Tesco Clubcard.

According to a post on Lewis’ website, an eye-watering £18 million worth of Clubcard vouchers are set to expire at the end of November.

In the post, he warns that Clubcard vouchers are only valid for two years from the date they were issued, meaning that if you don’t use them, you lose them.

Lewis warns that shoppers should check the date on the vouchers themselves or if they are lost, to check on the Tesco Clubcard website or app.

For those in no rush to spend their well-earned rewards, the Money Saving Expert founder is on hand to offer advice on how shoppers can not only extend the validity but double the value.

Lewis’ team at Money Saving Expert have tested a method that they say can extend the validity of soon to expire vouchers.

The site advises shoppers to: "Make a small purchase on the Tesco Clubcard Rewards page (not in store or on other Tesco pages) or donate to one of its partner charities.

"The remaining balance is credited back to your Clubcard account as points. So if you spend 50p using a £5 Clubcard voucher, you'll get 450 points back (worth £4.50).

"You can then swap your points for vouchers manually or wait for them to be converted with your next statement. The expiry date for these new vouchers will be two years in the future."

Lewis also advises on how those in possession of vouchers can double their value.

The vouchers can be redeemed online or in-store. Every 100 points accumulated equates to £1 which can be spent in Tesco.

But the value can be doubled if spent with one of Tesco’s reward partners which includes brands such as Disney+, Legoland, and Pizza Express.

With these brands every 100 points is worth £2, effectively doubling the value of the reward.