Up to 70 investment banking customers of Royal Bank of Scotland will have to pay to hold deposits with RBS from Monday when it will become the first UK bank to charge negative interest rates.

The decision is said to be connected to the European Central Bank’s negative deposit rate and not to the Bank of England’s decision this month to cut its main lending rate to a record low of 0.25%.

Reuters reported that RBS has contacted about 70 investment banking customers to warn them about the charges, which are expected to hit customers who trade futures and options contracts that have to be processed via clearing houses in Europe.

RBS told Reuters it is passing on the negative rates the clearing houses have charged to handle those trades since the ECB cut its base rate earlier this year.

“Due to the sustained low interest rate environment, RBS will now be passing the cost of holding such deposits on to a limited number of our institutional clients,” the bank said.

Bloomberg reported that some RBS institutional clients will have to pay interest on funds pledged as collateral when trading futures contracts.

RBS also wrote to around a million business clients in the UK last month to warn that it might be required to impose charges on deposits if the Bank of England introduced negative interest rates.