Prizes up to �1,000 are waiting to be claimed

Bond holders are being urged to check if they match the lucky numbers.

The amount of prize money which has not been collected throughout the UK has reached its highest level, at �23m.

There are five unclaimed Welsh prizes worth �1,000 each.

National Savings and Investments (NS&I), which looks after Premium Bonds, says it is keen to reunite winners with their money.

Relatively few people in Wales forget to pass on their new address when they move, however.

10FS154080 �1,000 (last known address in Clwyd) 16KK605158 �1,000 (Gwynedd) 16PP656806 �1,000 (Gwent) 21PT253106 �1,000 (Gwent) 05EL114895 �1,000 (Gwent)

Recent researcy by NS&I found that only 1% of people in Wales who moved house in the last 12 months forgot to pass on their details to all the financial organisations with which they deal.

But NS&I says despite having the best record in Britain, the amount of unclaimed money remains significant.

NS&I commercial director Gill Cattanach said: "Our aim is to reunite Bondholders with the �23 million in unclaimed prizes and we urge those customers who've forgotten to tell us they've changed address to get in touch to check if they are a winner."

There is no time limit on claiming, and each unclaimed prize is held until the winner can be tracked down.

The oldest unclaimed prize dates back to the first draw in June 1957.

NS&I said some people might have forgotten they have Premium Bonds which are entered into a prize draw each month.

Claimants can log on to the NS&I website and use the Premium Bond prize checker.

They can also visit a main post office and ask to see the supplement to the London Gazette.

They could also write to Premium Bonds, National Savings and Investments, Blackpool, FY3 9ZW.