The change will add £39m to its July prize fund although the odds of each £1 Premium Bond winning a prize will remain at 24,000 to 1.

Meanwhile, the Junior ISA interest rate will be increased from 3.4% to 3.65%, benefitting 89,000 young savers.

Dax Harkins NS&I chief executive, said: “This is now the sixth prize fund rate increase for Premium Bonds in just over a year, making it the highest it’s been in over 15 years. With the changes, we’re expecting to pay out more than £374m to winners in July with more higher value prizes.”

Sarah Coles, head of personal finance, Hargreaves Lansdown, said: “Premium Bonds have put on a burst of speed to catch up with the easy access market. They’d been biding their time since February, while the rest of the market pushed ahead, but this rise brings them back to winning form.

“The big change this month is that the number of £50 and £100 prizes has now overtaken the number of £25 prizes – with the smaller prizes being cut and the larger ones hiked. NS&I is aware that £25 isn’t what it once was, so it’s focusing its attention on slightly bigger prizes.

“There has been a bump in prizes all the way up to £100,000 – including 80 more £10,000 prizes and 160 more £5,000 prizes. It’s a sensible option – and will ensure that winning on the Premium Bonds remains an exciting day for more people.”

Current and new Premium Bonds prize fund rate and odds


Number and value of Premium Bonds prizes


Variable rate savings products