Hundreds of thousands of NatWest business customers were warned they could be charged for having a credit balance

Customers could be charged for depositing money in their accounts after one of Britain’s biggest banks took a step towards negative interest rates.

Hundreds of thousands of NatWest business customers have been warned that they could be made to pay a fee for having a credit balance. The announcement opens the way for a high street bank to introduce negative interest rates — with savers effectively penalised for depositing money — for the first time in Britain.

In a letter to customers, NatWest, whose parent is the taxpayer-owned Royal Bank of Scotland, said: “Global interest rates remain at very low levels and in some markets are currently negative. Dependent on future market conditions, this could result in us charging interest on credit balances. We’ll provide