(1) A head may refuse to grant an FOI request if access to the record concerned could, in the opinion of the head, reasonably be expected to -

(a) prejudice the effectiveness of tests, examinations, investigations, inquiries or audits conducted by or on behalf of an FOI body or the procedures or methods employed for the conduct thereof,

(b) have a significant, adverse effect on the performance by an FOI body of any of its functions relating to management (including industrial relations and management of its staff), or

(c) disclose positions taken, or to be taken, or plans, procedures, criteria or instructions used or followed, or to be used or followed, for the purpose of any negotiations carried on or being, or to be, carried on by or on behalf of the Government or an FOI body.

(2) Subsection (1) shall not apply in relation to a case in which in the opinion of the head concerned, the public interest would, on balance, be better served by granting than by refusing to grant the FOI request concerned.