The martial arts star was directing and starring in the sequel to 2003 hit Ong Bak when he disappeared. However, Sahamongkol president Somsak Techaratanapraset told local reporters that the film would still be finished in time for its December release in Thailand.
Although Jaa's exact whereabouts are unknown, his family told local press that the star suffered from stress during the shoot and had gone to meditate in the jungle.
The film, which started shooting in October 2006, was close to completing principal photography when Jaa went missing. The film's producer Prachya Pinkaew, who directed the first Ong Bak movie, said he would step in to edit the footage and maybe finish the directing.
Sahamongkol distribution chief Gilbert Lim said that some distributors had cancelled pre-sales contracts due to delays, although major buyers such as Germany's Splendid are still on board.
'We just hope he will come back and finish the film himself,' said Lim, adding that the setback shouldn't affect the studio's ability to deliver the film.
Lim also said that Sahamongkol had 'separated very amicably' with The Weinstein Company on the project. TWC took world rights outside the UK and Asia to the sequel in 2006 but handed back all except US rights last year.
Local press had speculated about financial mismanagement on the film, which prompted the local press conference. However, Somsak insisted that Jaa had not acted unlawfully.
'I guarantee that this is not a case of financial fraud, and I have no intention of pursuing any legal action against him,' he said.
Meanwhile, Sahamongkol is gearing up to release Nonzee Nimibutr's Queens Of Langkasuka in Thailand in October. The big-budget pirate adventure was originally scheduled for Sep 12 but was rescheduled out of respect for the release of Where The Miracle Happens, starring Thai princess Ubol Ratana and adapted from her book.