A fog of uncertainty’s descended on Middle-Earth and “The Hobbit,” following Guillermo del Toro’s stunning decision to ditch directing the back-to-back films.

Citing delays in getting a greenlight from co-financiers MGM and New Line, del Toro walked away from the gig Sunday — two days after blaming the hold-ups on the lack of a resolution to MGM’s ownership situation.

A New Line spokeswoman denied the helmer’s assertion, saying, “The impending MGM sale has nothing to do with the status of this project.” MGM had no comment.

“Hobbit” exec producer Peter Jackson said he’s continuing to work on the pics and will meet this week with execs from New Line and parent Warner Bros. to hire another director.

Jackson told a Kiwi newspaper he hadn’t completely ruled out directing “The Hobbit.”

“If that’s what I have to do to protect Warner Bros.’ investment, then obviously that’s one angle which I’ll explore,” Jackson said in an interview with the Dominion Post.

However, he added that stepping in as “Hobbit” director would be difficult as he had signed writer and director contracts for two other unidentified films.

“The other studios may not let me out of the contracts,” Jackson told the newspaper.

Jackson’s a producer with Steven Spielberg and Kathleen Kennedy on “The Adventures of Tintin: Secret of the Unicorn” for Paramount, DreamWorks and Sony, due out at the end of next year. He’s also expected to direct the “Tintin” sequel. Jackson had said Sunday that he wasn’t anticipating any delay or disruption to pre-production work on “The Hobbit” and indicated that the pics were on track for releases in December 2012 and December 2013.

To make those release dates, production would probably have to begin by the end of this year.

Jackson also expressed sympathy Sunday for del Toro’s plight, saying the “protracted” development time on the two films had compromised del Toro’s commitment to other projects.

“The bottom line is that Guillermo just didn’t feel he could commit six years to living in New Zealand, exclusively making these films, when his original commitment was for three years,” he said in a statement to the One Ring website.

The “Hobbit” screenplays have been submitted to the studios and del Toro said he’ll continue to co-write the screen-plays with Jackson, Fran Walsh and Philippa Boyens.

“In light of delays in the setting of a start date for filming ‘The Hobbit,’ I am faced with the hardest decision of my life,” del Toro said. “After nearly two years of living, breathing and designing a world as rich as (author J.R.R.) Tolkien’s Middle-Earth, I must, with great regret, take leave from helming these wonderful pictures.”

New Line shares financing rights with MGM/UA, which bought the original rights in 1969. The films have not been officially greenlit by New Line and MGM — which would trigger calculation of the budget and set a start for lensing in New Zealand.

MGM’s debtholders are in the midst of sorting out the future of the studio, which is hobbled by debts of $3.7 billion. MGM management put the Lion up for sale in November but was unable to find a buyer willing to meet its $2 billion-plus asking price.

As a result, feature production at MGM is at a standstill. MGM recently obtained a fifth extension on its debt payments until mid-July in support of the studio’s efforts to improve its financial position.

Producers Michael G. Wilson and Barbara Broccoli announced in April that they put plans on hold for the next James Bond pic due to the “continuing uncertainty” surrounding the future of MGM.

“The Hobbit” films, which are being exec produced by Jackson and Walsh, are based on the adventures of Bilbo Baggins — who obtains the ring that was the centerpiece of “The Lord of the Rings” trilogy of books and films.

In his posting, del Toro said he remained grateful to Jackson, Boyens and Walsh along with New Line and Warner Bros. and to all his crew in New Zealand.

“I’ve been privileged to work in one of the greatest countries on Earth with some of the best people ever in our craft and my life will be forever changed,” he added. “The blessings have been plenty, but the mounting pressures of conflicting schedules have overwhelmed the time slot originally allocated for the project. Both as a co-writer and as a director, I wish the production nothing but the very best of luck and I will be first in line to see the finished product. I remain an ally to it and its makers, present and future, and fully support a smooth transition to a new director.”

Del Toro had said two days earlier at a news conference for “Splice” — which he’s producing — that all the “Hobbit” creatures had been designed.

“We’ve designed the sets and the wardrobe. We have done animatics and planned battles sequences. … We are very, very prepared for when it is finally triggered.”

Del Toro’s directing credits include “Pan’s Labyrinth,” “The Devil’s Backbone” and the two “Hellboy” pics. He committed to direct “The Hobbit” films in April 2008, with the pics expected at that point to come out at the end of 2011 and 2012.

It’s unclear which project del Toro will tackle next. In September 2008, he made a longterm commitment to Universal, where he has a first-look deal, on an adaptation of Dan Simmons’ novel “Drood” and remakes of “Frankenstein,” “Dr. Jekyll and Mr. Hyde” and “Slaughterhouse-Five.”

The Mexican native also set up the Double Dare You production banner for animated films at Disney last fall.