Guillermo Del Toro has dropped out directing “The Hobbit” movies due to the ongoing delays in getting the films greenlit.

Del Toro made the surprise announcement Sunday on The One Ring web site, adding that he will continue to co-write the screenplays based on J.R.R Tolkien’s “The Hobbit.”

“In light of ongoing 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 in a statement. “After nearly two years of living, breathing and designing a world as rich as 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. Reps for New Line and MGM were not immediately available.

Del Toro has been writing the scripts with Peter Jackson, Fran Walsh, Phillipa Boyens and director Guillermo del Toro but the back-to-back-films had not been officially greenlit by New Line and MGM — which would trigger calculation of the budget and setting a start for lensing in New Zealand. But MGM’s ownership has remained unresolved in the wake of the struggling studio putting itself up for sale in November.

“The Hobbit” films are being exec produced by Jackson and Walsh with MGM and New Line co-financing. The two pics are based on JRR Tolkien’s novel, which follows the adventures of Bilbo Baggins, who obtains the ring that was the centerpiece for “The Lord of the Rings.”

In his posting, Del Toro said he remained grateful to Jackson, Boyens and Walsh along with New Line and Warner Brothers 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” that “The Hobbit” pics remained in limbo until the MGM financial crisis was resolved.

“It’s not greenlit,” he told reporters. “That’s categorical. We’ve been caught in a very tangled negotiation. There cannot be any start dates until the MGM situation gets resolved. They do hold a considerable portion of the rights.”

He also said that all the creatures had been designed, adding, “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 directing project del Toro will tackle next. In September 2008, he made a long-term commitment to Universal, where he has a first-look deal, with a quartet of directing projects including an adaptation of the Dan Simmons novel “Drood” and remakes of “Frankenstein,” “Dr. Jekyll and Mr. Hyde” and “Slaughterhouse-Five.”

Jackson said in a statement that the “protracted” development time on the two films had compromised del Toro’s commitment to other long term 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.

Jackson also said he’ll meet this week with execs from New Line and parent Warner Bros to hire a new director and noted that he did not anticipate any delay or disruption to ongoing pre-production work.