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A movie version of Kiwi classic Under the Mountain, starring Sam Neill, is in jeopardy after a last-minute funding hitch.

More than 40 per cent of cash pledged to the remake of the popular 1980s TV series _ based on writer Maurice Gee's 1979 book _ has been pulled by British company Capitol Films.

Producer Richard Fletcher said he was "shocked" by the developments that had forced him to reassess funding options.

"Basically we were in active pre-production, and this significant financier defaulted just over a week before we were due to start principal photography. We got caught up in much wider issues that company has."

The fantasy adventure tale, set in the heart of Auckland, is about teenage twins who must face evil forces lurking beneath the region's volcanoes.

Weta Workshop in Wellington is set to create the underground creatures in the movie, as well as the special effects.

Mad Max 2 actor Bruce Spence co-stars, and two teenagers have signed to play redhead twins Rachel and Theo.

Capitol Films, who signed a contract and made a part-payment on Under the Mountain, has been involved in numerous successful movies over the past 17 years, including Gosford Park and Adaptation.

According to the LA Weekly News, A-listers Helen Mirren and Joe Pesci are among the Hollywood actors and directors left in limbo by the funding woes.

All production on Under the Mountain, was suspended on April 28. A plywood house built for exterior scenes in an Auckland park was removed earlier this month, and shooting had been set to start last month.

The project has funding from the Film Fund, New Zealand on Air and TVNZ.

Fletcher, a director of Redhead Films with the movie's writers Matthew Grainger and Jonathan King, will approach the Screen Production Investment Fund for more money.

He said help from those agencies, and significant international pre-sales left him hopeful filming could start in August. "We just want to get things going as soon as possible. Sadly this is not totally uncommon for the film industry."

The core cast is still contracted and producers are attempting to retain as many key crew members as possible. At least one crew member contacted by the Herald on Sunday was unsure if he could rejoin the project at a later date, due to conflicting obligations.

If filming starts in August, Fletcher said it would be ready next May and released later next year.