The world’s largest banks have been accused of evading inquiries about their financing of ethically and environmentally dubious companies by arguing they are unable to disclose client information — despite routinely doing so at other times.

BankTrack, a pressure group, said it had made 150 enquiries of 31 large international banks over five years, between 2012 and 2017, asking them to confirm involvement in controversial financings, and found large inconsistencies in policies.