The Chancellor missed a prime opportunity to boost the UK’s green economy with his new ISA savings allowance, according to Triodos Bank.

Six years ago as Shadow Chancellor George Osborne raised the idea of a Green ISA, with cash ring-fenced for green investment.

The self-declared ethical bank has asked why he didn’t put this into his Budget on Wednesday.

Mr Osborne did tinker with the savings scheme – announcing cash and stocks ISAs would be merged into a single New ISA with a yearly tax-free savings limit of £15,000.

Huw Davies, Head of Personal Banking at Triodos Bank said: “This increase could have been used to scale-up the green economy… Less than two weeks have passed since the House of Commons cited a £12bn hole in the funding needed to finance the transition to a low-carbon economy.

“The funds likely to be raised by the uplift could have helped to plug the funding gap, injecting capital into the green economy while still providing a welcome tax incentive to UK savers.”

The bank has claimed Green ISAs could be introduced at “little or no cost”.

More than £57 billion was invested in ISAs in the last tax year alone, by 14.6 million subscribers.