The Civil Aviation Authority says the Gupta party plane has violated South African aviation regulations.
It has emerged the plane did not have a Foreign Operator Permit (FOP).
The CAA is considering taking what it calls "enforcement action".
The Airbus A330 belongs to Jet Airways.
It touched down at Waterkloof Air Force Base on Tuesday, carrying wedding guests headed for the Gupta wedding extravaganza at Sun City.
On Thursday, it was moved from the National Key Point to OR Tambo International, at the behest of the SANDF.
The CAA has given some fresh insight into the procedure that should have been followed by the aircraft's operator.
According to the law, the operators should have submitted a written application to the Director of Civil Aviation, formally requesting permission for the aircraft to land at a military aerodrome.
If the Defense Minister had granted permission that application would then have been forwarded to the CAA.
But the CAA has now confirmed that no such application was received.
The operator also didn't bother to notify South African aviation authorities about their intention to land and allow the CAA to review the documentation prior to landing, conduct safety audits and verify crew licences.
None of this happened.
The Party plane scandal has gripped the nation, causing outrage on social networks and sending government scrambling to explain how a civilian chartered jet could have landed at a key strategic airbase seemingly without any executive approval.