Comcast Corp. is ready to go to war with Walt Disney Co.

The cable giant confirmed on Tuesday that it may make an offer for a wide swath of 21st Century Fox Inc.’s entertainment assets, a business that Disney has already agreed to buy for roughly $52 billion.

The move threatens to escalate a bidding contest that’s already underway over Fox’s European satellite business -- and further complicate a global game of M&A chess that’s being waged by the biggest media companies.

Comcast “is considering, and is in advanced stages of preparing, an offer for the business that Fox has agreed to sell Disney,” the company said in a statement. “Any offer for Fox would be all-cash and at a premium to the value of the current all-share offer from Disney.”

While no final decision has been made, Comcast said its work to finance the offer -- and preparation to file key regulatory statements -- is “well advanced.” A person familiar with the discussions said earlier this month that Comcast was mulling such a step. Comcast was talking to investment banks about obtaining bridge financing for the all-cash deal, the person said at the time.

A counterbid would roil a plan by Disney Chief Executive Officer Bob Iger to bolster the company’s dominance in entertainment. Fox agreed in December to sell its film and TV studios, cable channels including FX and National Geographic and other assets to Burbank, California-based Disney in an all-stock deal. Comcast said at the time that it “never got the level of engagement needed to make a definitive offer.”

Disney plans to use the bigger stable of TV and movie properties in part to stream more content directly to consumers.

“If Comcast won these assets from the arms of Disney, it would be a devastating blow to Iger,” Daniel Ives, an analyst at GBH Insights, said in a note.

Comcast investors gave a tepid reaction to the idea. The stock declined 2.1 percent to $31.82 in early trading on Tuesday. Even before the announcement, Comcast’s expansion plans have weighed on the shares, which are down 19 percent this year.

Shares of Fox climbed as much as 3.5 percent to $39.50, while Disney declined up to 1 percent to $103.

Comcast is already making an ambitious push in Europe. The Philadelphia-based company made a 22 billion pound ($30 billion) offer to acquire the 61 percent stake in U.K. satellite broadcaster Sky Plc that Fox doesn’t already own. Fox and Disney also are interested in buying the business.

Comcast won approval on Monday from the U.K. government to move ahead with its offer for Sky.

Comcast’s plans for Fox, meanwhile, may hinge on the fate of another deal: AT&T Inc.’s attempt to acquire Time Warner Inc. If that transaction is thwarted on antitrust grounds, Comcast would have less reason to pursue Fox.

Like a Comcast deal for Fox’s assets, the AT&T proposal is an example of a large TV distributor attempting to own a TV programmer -- what’s known as a vertical merger. A judge is slated to rule next month whether to block or allow the AT&T transaction.

Both Disney and Comcast also are looking to expand overseas and offer more content directly to consumers. Fox’s assets would help both companies achieve these goals, said Paul Sweeney, an analyst at Bloomberg Intelligence.

That’s why a bidding war could be intense.

“Disney is likely to put up quite a fight,” he said.