Comcast has confirmed rumors that it plans to derail Disney’s bid for most of 21st Century Fox.

In a statement released by Comcast today, the company says it is in the “advanced stages” of putting together an offer for the businesses that Fox agreed to sell to Disney for $52.4 billion in stock in December.

Any deal Comcast makes for Fox would be all-cash, according to the statement.

While Fox would have to pay a breakup fee of $1.52 billion if they pull out of the Disney deal, Comcast says that its bid would more than cover that cost, putting the offer “at a premium to the value of the current all-share offer from Disney.”

There could be some potential tax hurdles to Comcast’s bid, however. While Disney's stock offer would allow Fox to spin off its assets tax-free, a cash offer from Comcast would result in a taxable spin, sources told CNBC.

Disney's drive to broaden its footprint in video streaming to compete with Neflix would likely take a blow if Comcast’s bid is successful. The deal includes Fox’s existing 30 percent stake in Hulu, as well as a 50 percent share in Endemol Shine Group (the satellite service of Star India) and a 39 percent stake in European satellite broadcaster Sky.

While 21st Century Fox executive chairman Lachlan Murdoch has said that Fox is “committed to our agreement with Disney,” he concedes that the company’s board “are aware of their fiduciary duties on behalf of all shareholders.”