It depends on the structure of Co-operative banks. Some co-operative banks have exclusive finance from parties and some exclusive from RBI/State Govt.
The rule that applies to all public authorities should be uniformly applied to co-op banks also.
The yard stick is "Without contribution of such amount, the entity ceases to exist, which is substantial contribution by Govt. as defined in RTI Act for declaring a Public Authority under RTI Act.
The essence is that government should have substantial contribution in capital of that Co-op bank.