The retailer said an unusually large number of Clubcard vouchers have been sitting unclaimed for nearly two years and will expire on 29 February.

These unclaimed vouchers could cover more than 650,000 weekly grocery shops, Tesco said.

They could be worth up to triple their value when used with one of the retailer’s 150 reward partners including Pizza Express and Thorpe Park.

Clubcard members can collect points when shopping in-store and online. Tesco turns these into vouchers to help save on future shops or days out.

Members receive one point for every pound spent.

You can check the number of points and vouchers you have via the Clubcard app.

Vouchers are valid for two years and can be used for shopping trips online and in-store.

Misplaced paper vouchers can also be checked in the Clubcard app, which is available on smartphones from iTunes or on Google Play.

Alessandra Bellini, Tesco chief customer officer, said: “Clubcard is our way of helping customers to get the very best value when shopping with us, and we want to help them make the most of it.

“We also understand that our customers lead busy lives and may forget about the points and vouchers that they’ve built up over time.

“With a large number set to expire at the end of the month, we are encouraging people to check the Clubcard app to see if any of these unused vouchers are theirs.”