Manchester United are investigating the possibility that Gabriel Heinze was tapped up by Liverpool.
United refused to sell the Argentina defender to their arch rivals despite Liverpool matching their valuation.
Heinze's attempt to push through a move to Anfield was rejected by a Premier League arbitration earlier this week.
The United star has since signed for Real Madrid in an £8million deal.
But Fergie is still fuming over Liverpool's bid and confirmed chief executive David Gill is leading an inquiry into the Merseysiders' conduct.
He said: “We are looking at Liverpool’s whole role in this.
“We are not letting them off with it. That is what we are investigating.”
Asked whether he was alleging Liverpool had tapped up Heinze, Fergie replied: “We will see how it comes out.
“David Gill is working on that at the moment. We will get to the bottom of it.”
Fergie was also quick to hit back at BenitezÂ’s jibe that United enjoy favouritism in the drafting of the fixture list.
He stormed: “It is disappointing stuff.
“He talks about the fixtures. He should have seen our fixtures over over the last two or three seasons.
“There was never any chance of Liverpool winning that case, so Rafa clearly did not read the Premier League rules. It is just churlish.”