Movie chiefs could switch the site of their planned "Valleywood" film studio from a site near Bridgend to the former LG plant in Newport.
Lord Attenborough is chairman of the studios project
Dragon International Studios was due to open a studio complex - bigger than those at Pinewood and Shepperton - at an opencast mine at Llanilid in 2004.
It promised to create thousands of new jobs.
But the man heading the project is frustrated with delays in getting Welsh Assembly grants and could take the £350m complex elsewhere.
Along the M4, Newport's empty former LG Semicon plant - one of Wales' largest, most modern factory spaces - has already been offered as an alternative.
Chaired by actor and director Lord Richard Attenborough, Dragon won planning approval for brownfield land at Llanilid, near the M4, in December after 18 months of negotiations.
Plans include a 160-acre studio complex, sound stages, creative departments, and music recording studio.
'Valleywood' would be bigger than Pinewood or Shepperton
Developers promised to create 1,710 jobs directly and forecast thousands more.
They pledged to re-train former miners and steelworkers for hands-on work in the film industry - a boost for Rhondda Cynon Taff, where the council worked hard to lure the prize project.
Construction was due to begin this spring, but Dragon chief executive Stuart Villard has blamed the Welsh Assembly Government for a hold-up.
"We have been waiting for months and months for a response to our application for grants, but we've had no response," he told BBC News Online.
We can't get the foundations built or anything
Dragon International Studios
"We can't get the project going. We can't lay the foundations or build anything - why should I?"
Dragon had applied to the assembly government for regional selective assistance grants, which will give it essential cash in return for a promise to create jobs.
On Thursday, Dragon revealed an unnamed party had offered it Newport's former LG Semicon plant, which has been empty since 1998 after a deal to bring thousands of jobs failed.
"We're committed to Llanilid but I have looked around the LG facility," Mr Villard said.
"If we don't get the letters (confirming grants) for Llanilid, we could go to LG or any other site."
A switch could see Newport gain jobs earmarked for Llanilid, but Mr Villard said he would retain the pledge to re-train skilled, unemployed people at any new location.
Talks have been going on for somet time to fill the LG Semicon site
Plaid Cymru has accused the Labour-run assembly government of "trying to poach this project from a deprived Objective One area to compensate for job losses in the LG plant".
Objective One areas are in the west Wales and south Wales valleys and are entitled to millions of pounds of European aid.
But the assembly government said: "Interest continues to be focused on the Llanilid site for a major studio complex.
"But, ultimately, the company will need to make its own commercial judgement on its preferred site for development."
On the subject of grants, a spokesman added: "The Welsh Assembly Government only offers regional selective assistance when it receives what it considers to be a truly viable business case.
"The assembly government and Welsh Development Agency will be in touch with Dragon International soon to discuss the next stop."