is angry that the current national broadcasters could have their licences extended without having to contest an auction.
TalkSport's licence is due to expire by December 2012, Classic FM's expires by September 2011 and Absolute's FM licence by April 2012.
Current broadcasting rules decree that the licences should be auctioned to the highest bidder, but in the Digital Britain report this week it was proposed that TalkSport, Classic FM and Absolute Radio could avoid their licences going to auction in return for investment in digital radio switchover.
According to the Daily Telegraph, Mackenzie, who now writes a column in the Sun, is threatening to derail this plan by taking legal action.
Mackenzie, in the report, said: "The bottom line is there would be a queue a mile long to bid for these three national licences and interested parties would pay millions for them which would go straight to the Exchequer.
"People like me are willing to pay a lot for one of these national licences which are up for renewal soon.
"If the Government presses ahead with this, I will take legal action and go to the High Court. There is nothing in the current broadcasting act which allows the automatic roll-over of these licences."
The licences have also attracted Sir Richard Branson, whose Virgin Radio International is understood to have expressed interest to Ofcom.