The sudden collapse of celebrity chef Jamie Oliver's restaurant empire in the United Kingdom will leave more than 1,000 employees out of work and Oliver’s dream of transforming high street dining in tatters.

All but three of Oliver’s 25 U.K. restaurants have been placed into administration (bankruptcy protection) and will eventually be closed. The only operational restaurants are three outlets at Gatwick airport that will remain in business even as administrators seek a buyer.

On Tuesday, KPMG were appointed administrators of the Jamie Oliver Restaurant Group, which opened its first restaurant, Fifteen, in 2002. The Jamie Oliver Restaurant Group includes 22 Jamie’s Italian outlets, plus the Fifteen and Barbecoa restaurants in London and a Jamie’s Diner at Gatwick airport.

Oliver launched Jamie's Italian with a focus on casual, mid-market dining with quality ingredients.

Oliver tweeted, “I’m devastated that our much-loved UK restaurants have gone into administration. I am deeply saddened by this outcome and would like to thank all of the people who have put their hearts and souls into this business over the years.”

The restaurants placed on administration does not affect more than 61 overseas outlets, however. This total includes 25 Jamie’s Italians and Fifteen in Cornwall run by franchisees.

A 10-year deal with the U.S. caterer Aramark to open franchise sites in universities and hospitals in the United Kingdom and overseas is also unaffected.

Oliver, 43, is the latest victim of the brutal competition in Britain's casual dining market, which is seeing a continuing decline in the number of chain restaurants amid consumer worries over Brexit.

Sales at Jamie’s Italian plunged by nearly 11 percent in 2018 to $128 million (£101 million) as it closed 12 restaurants and fired 600 employees. Oliver’s food magazine, Jamie, shut down in October 2017 after almost 10 years, dragged down by the financial misfortunes of the restaurant chain.

“I appreciate how difficult this is for everyone affected,” he said. “We launched Jamie’s Italian in 2008 with the intention of positively disrupting mid-market dining in the UK high street, with great value and much higher quality ingredients, best-in-class animal welfare standards and an amazing team who shared my passion for great food and service. And we did exactly that.”

Gemini Jamie Oliver
Chef Jamie Oliver was born May 27. He is pictured at Magic Radio on Sept. 4, 2017 in London, England. John Phillips/Getty Images

Oliver thanked his employees and suppliers who “put their hearts and souls into the business.”

Expensive full-service restaurants such as Jamie’s Italian are being hard hit by British consumers favoring cheaper coffee shops, cafés, dine-in markets and in-store cafés. Sales at full-service restaurants are down 6% year-on-year, according to the market research firm Kantar.