LONDON — The celebrity chef Jamie Oliver put his British restaurants into administration , a form of bankruptcy protection, on Tuesday, after the chain struggled with debt and an increasingly saturated market in recent years.

All but three of Mr. Oliver’s 25 restaurants will close, and about 1,000 employees will lose their jobs, according to KPMG, the firm hired to administer the business for creditors.

The remaining outlets, two Jamie’s Italian restaurants and a Jamie’s Diner at Gatwick Airport, will stay open indefinitely.