HSBC bank has written to Finsbury Park Mosque and other Muslim organisations in the UK to tell them that their accounts will be closed.
The reason given in some cases was that to continue providing services would be outside the bank’s “risk appetite”.
The wife and teenage children of a man who runs a London based Islamic think tank have also been contacted.
HSBC said decisions to close accounts were “absolutely not based on race or religion”.
“We do not discuss relationships we may or may not have with a customer, nor confirm whether an individual or business is, or has been a customer.
“Discrimination against customers on grounds of race or religion is immoral, unacceptable and illegal, and HSBC has comprehensive rules and policies in place to ensure race or religion are never factors in banking decisions.”
The bank said it was “applying a programme of strategic assessments to all of its businesses” after a $1.9bn fine in 2012 over poor money-laundering controls.