Jamie Oliver has said he is "devastated" after his restaurant chains appointed administrators, putting more than 1,000 jobs at risk.

The business, which includes Jamie's Italian, Barbecoa and Fifteen, has appointed KPMG to oversee the process, with a more detailed announcement expected later on today.

Mr Oliver took to Twitter to express his sadness, saying he was "devastated" and thanking those who "put their hearts and souls into this business over the years".

In an official statement, the chef added: "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."

Around 1,300 people are estimated to work for the UK business.

The process does not affect Mr Oliver's other companies, which handle his media and licensing deals, while the international branch of Jamie's Italian is also unaffected.

Fifteen Cornwall, which operates under a franchise, is also not involved.

It follows a hunt for a new investor in the Jamie's Italian brand, with a number of private equity firms touted as mulling bids for a stake in the business.

Mr Oliver's restaurant empire has taken a few knocks over the past two years.

In 2018 Jamie's Italian shuttered 12 of its 37 sites through a Company Voluntary Arrangement (CVA).

The TV personality's steak house, Barbecoa, also went into a pre-pack administration, leading to the closure of its Piccadilly branch.

Overseas, five branches of the Australian arm of Jamie's Italian was sold off last year, while another was put into administration.

Despite the troubles, which forced Mr Oliver to pump £13 million of his own money into his Italian chain, he told Press Association earlier this year that casual dining was primed for a comeback.