An inquiry into the rapid release of SIS documents to embarrass Phil Goff when he was Labour leader will deliver its findings tomorrow and it's expected to implicate the Prime Minister's office.

The documents were handed over to blogger Cameron Slater who it's claimed got preferential treatment after being tipped off by John Key's office.

The inquiry has been carried out by the Inspector General of Security and it's expected to show the Prime Minister's then so called black ops man Jason Ede tipped off Mr Slater who made the documents public.

The damning report is expected to implicate the then SIS Director Warren Tucker in the campaign to embarrass Mr Goff and the spy organisation will be asked to formally apologise to the Labour MP.