Dutch banks ABN Amro and ING have been told to pay an extra €200 million in compensation to customers who were overcharged interest on credit cards and mortgages.

The financial complaints authority Kifid had already ordered the banks to repay customers who borrowed money at a variable rate of interest. It ruled that the banks had breached their own lending terms by not adjusting their rates immediately when market rates fell.

ABN Amro and ING had earmarked €340 and €180 million respectively to cover the cost of compensation, but Kifid has now said they must include compound interest.

Rabobank, which was also subjected to the original ruling, has already included compound interest – the interest accrued on earlier interest payments – in its calculations.

The ruling was the outcome of several cases brought by Rob Goedhart, chairman of consumers’ campaign group Stichting Geldbelangen.

Goedhart has calculated that Dutch banks have set aside €965 million to compensate customers, but argues the figure is still €1bn too low because banks work on the basis that not all disadvantaged customers will come forward to claim their money.