More than £105 million of Premium Bond winnings is waiting to be claimed by savers — including 11 prizes of £100,000.

National Savings and Investments (NS&I), the Treasury-owned bank, said 2.6 million prizes were unclaimed, with more than 140 of those prizes worth £10,000 or more.

Most of the unclaimed prizes are small — more than 1.8 million are worth £25 — but on top of those 11 prizes of £100,000 are 19 of £50,000, 38 worth £25,000 and 75 of £10,000.

Premium Bonds work like a lottery, with each £1 bond having a unique number that’s entered into the monthly draw. The prizes range from £25 (of which there are more than two million a month) to two £1 million jackpots. Unlike with standard savings accounts, which have a guaranteed return, you may win nothing, but unlike savings interest the prizes are tax-free.

Premium Bond prizes become classified as “unclaimed” if they have not been collected within 18 months. There is no time limit to claiming a prize, no matter how long ago it was drawn. Data is available dating to 1957, when Premium Bonds began.