San Francisco  - National Semiconductor Corp, one of the world's largest manufacturers of mobile phone chips, will cut over 1,700 workers, or about a quarter of its work force, the company said Wednesday.

The layoffs will hit all areas of the company and will be carried out in two phases with 850 redundancies occurring immediately and 875 taking place over the coming months, the Silicon Valley-based company said.

National Semiconductor will also close two plants in China and Texas as it attempts to deal with a precipitous decline in demand for its chips, which power phones made by the world's largest mobile phone manufacturer, Nokia, and many others.

"The worldwide recession has impacted National's business as demand has fallen considerably," Chief Executive Officer Brian Halla said in a statement. "The actions we announced today will help us remain competitive."

The company will take a charge of between 160 million dollars and 180 million dollars in expenses related to the job cuts. (dpa)