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

Over 400 bond holders across the country have failed to claim prizes worth as much as �1,000 each.

The government backed savings provider NS&I has said the old county of South Glamorgan has the most unclaimed prize money in Wales - over �150,000.

The company's premium bond manager Sally Swait said the oldest unclaimed prize dates back almost 50 years.

"There is no time limit on claiming," she said. "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."

It's remarkable that we need to remind customers to claim any prize, particularly those worth �1,000! Sally Swait

NS&I notifies customers of their winnings by writing to them directly. The company has said that it is the failure to notify changes in address that means so much money remains in the coffers.

"Some people might not be aware they have premium bonds, which are entered into a prize draw each month," said Ms Swait.

"They might not remember making their original investment or perhaps they, like many, were given Premium Bonds as a child and have simply forgotten about them.

"There are at least 35 unclaimed prizes values at �1,000 each in Wales.

"It's remarkable that we need to remind customers to claim any prize, particularly those worth �1,000.

"We're standing by to give away over �850,000 in unclaimed prizes and urge customers to get in touch to check if they are a winner."

The top three regions in Wales are South Glamorgan at �156,775, Gwent at �141,1875 and Mid Glamorgan at �131,125.