The 69-year-old Bridge of Spies director said that Mr Jackson is working on a secret project for his company Amblin Partners, reports Vanity Fair.
On a promotion tour for his latest movie The BFG, Mr Spielberg revealed: "Peter was so busy with The Hobbit that it took him away from Tintin and he's doing another film for my company now."
Mr Spielberg disclosed that Mr Jackson is ready to continue with the sequel to the 2011 saga The Adventure of Tintin but only after the newly signed project.
"It's a secret. Nobody knows about it. Then after that, he'll do Tintin," he said.
Maker of The Hobbit trilogy, Peter Jackson, who was also the producer of Tintin, had been signed by Steven Spielberg to direct the sequel to it.
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