PHOTO: The CFMEU says it fears for all 900 construction jobs on the site. ABC News: Elise Kinsella

Up to 900 construction jobs on a Gold Coast high-rise development site could be at risk amid “unprecedented” problems, the construction union says.

Hundreds of workers on the $1 billion Jewel resort development site in Surfers Paradise are striking for a second day.

The CFMEU said 150 workers effectively lost their jobs on the Surfers Paradise project last week after builder Multiplex sent a message to some contractors drastically reducing their work.

The union’s assistant state secretary Jade Ingham said workers and the unions haven’t been told the full story about what is going on.