The Oscar-winning film-maker Sir Peter Jackson has been admitted to hospital in New Zealand for surgery that will further delay filming of his forthcoming two-part adaptation of JRR Tolkien's fantasy tale The Hobbit.

Jackson complained of acute stomach pains earlier this week, which were diagnosed as a perforated ulcer. His condition is not serious but his admission to the Wellington hospital yesterday is just the latest delay for a project which has been stymied by funding problems and a highly publicised industrial dispute.

The shoot was planned to start in mid-February but will now have to wait until Jackson has made a full recovery from his operation. The Hobbit is the prequel project to the New Zealander's Lord of the Rings trilogy, which drove all before it at the global box office between 2001 and 2003.

Melissa Booth, Jackson's publicist, said: "Sir Peter is currently resting comfortably and his doctors expect him to make a full recovery. The surgery is not expected to impact on his directing commitment to The Hobbit beyond a slight delay to the start of filming."

Guillermo Del Toro, who was originally set to direct the two films, dropped out last year after ongoing financial travails at studio MGM caused long delays in shooting. Jackson, 49, then stepped up to direct from a producing and writing role, but was almost immediately faced with a union boycott over pay and conditions that was only resolved after the New Zealand government stepped in to reassure Hollywood executives with financial concessions.

The two films are currently scheduled for release in December 2012 and December 2013 respectively. Ian McKellen and Andy Serkis recently confirmed they will reprise their roles as Gandalf and Gollum, with Martin Freeman set to play Bilbo Baggins, the titular hero.