Bad news for snails. Heston Blumenthal is to open a new restaurant in London next year with treble the space for diners as at his three-Michelin star restaurant, Fat Duck.

The chef, whose business has been recovering after a mystery illness struck down more than 400 diners, will open the restaurant at the Mandarin Oriental Hotel in Hyde Park in autumn next year, The Independent has learnt. The Fat Duck in Bray, Berkshire, can seat 45; the new restaurant will seat 140.

The long-rumoured move will greatly increase Blumenthal's earning power, putting him in the same multi-restaurant league as chefs such as Gordon Ramsay and Jamie Oliver. It will also expose him to the bigger financial risk which has proved the undoing of chefs such as Marco Pierre White, who expanded after running a single acclaimed restaurant for years.

Blumenthal has run the haute cuisine Fat Duck in the wealthy commuter village of Bray since 1995, turning it into one of the world's finest restaurants.

He also co-owns the nearby Hinds Head pub, which specialises in re-inventing historic British food. He has been in discussions about opening at the Mandarin Oriental for months.

The restaurant will serve lunch, dinner and afternoon tea. Ashley Palmer Watts, who has been the group executive chef at the Fat Duck for nine years, will head the kitchen. Adam Tihany will design the interior using materials such as wood, leather and iron.

No menu was disclosed but Blumenthal's spokeswoman indicated the venue would follow in the Fat Duck's footsteps, featuring the chef's "inimitable style of culinary alchemy, with a menu influenced by his research and discovery of historic British gastronomy".

The Fat Duck is known for its "molecular gastronomy" – a phrase Blumenthal dislikes but which emphasises his scientific approach to taste and flavour. Dishes on the £125-a-head tasting menu include "nitro green tea", bacon and egg ice cream, and mollusc-inspired porridge.

Blumenthal said: "I am thrilled at the prospect of opening a restaurant in such a central London location. I have great respect for the Mandarin Oriental brand and working in partnership with the hotel group is a natural step and one which offers an exciting opportunity."

The Mandarin said it was "delighted" to embark on the venture, which has been the talk of dining circles for months. David Nicholls, the Mandarin's corporate director of food and a long-time friend of Blumenthal, said of the chef: "I have always shared his enthusiasm for English recipes and have enjoyed working with him to help develop talented British chefs through the Roux Scholarship programme."

Blumenthalhas been slowly expanding his commercial activities, filming two BBC series about his quest for perfection. Last year he signed a three-series deal with Channel 4. He has also published several books.