Bank account statement issued to unauthorised person

Banks are public bodies.As per RTI if any person ask the statement of account, the banks must provide . Or else If court order to bank to issue such statement, the bank must abide the court orders. 

Ask legal advice to practicing lawyer

Banker is bound to keep secrecy of your account and transaction, instructions are as under:

Duty of Secrecy: Sec 13 of Banking Companies (Acquisitions & Transfer of Undertakings)
Act 1970, binds the bank not to disclose the information of the customers except when they
are required to do so under law i.e. giving information to Courts, Income Tax Dept, Police,
Enforcement Directorate etc. The important aspects of duty to maintain Secrecy are as
under;
· The duty to maintain Secrecy is the statutory obligation.
· This duty has to be observed even when same persons have joint Account are maintaining
separate independent Accounts. For example, husband and wife maintaining a joint
Account and the wife also maintaining an independent Account with the same branch or
any other branch.
· The duty of maintaining Secrecy is not limited to particular type of entries, i.e., only
withdrawals or only credit entries. It is applicable for all the transactions.
· Though even when the Account has been closed, or the customer is dead, the Banker-
Customer relationship come to an end, but the duty of the bank not to disclose the
particulars of the Account remains there.

I disagree with Ramachary to the extent Banks are Public bodies and the rest of his answer is ok.  And I completely agree with Rajendra K.Goyal.

Providing statement of a/c to a third party ( including spouse) without authority of the customer is illegal as per banking law and practice.