Naked Chef: I do use Sainsbury's

Naked Chef Jamie Oliver has hit back at reports that he does not shop at the supermarket chain he endorses, claiming he is in Sainsbury's "at least twice a week", and his grandmother will feature in the new Sainsbury's television advert.

"My wife is in there every day," the 25-year-old chef joked as he opened the new-look Sainsbury's flagship store in the Cromwell Road today.

Earlier this week, Two Fat Ladies star Clarissa Dickson Wright forced him to admit that his new restaurant, Monte's in Sloane Street, doesn't buy anything from Sainsbury's and accused him of "selling out".

However, Jamie said today: "No restaurant buys from a supermarket - it's not cost-effective. But I think Sainsbury's is a great supermarket chain. All the food in the photos in my last book was from Sainsbury's and I wasn't working for them then. They have always been ahead on organic food and I opened a Sainsbury's in Greenwich because it was trying to be much more environmentally friendly.

"I go to my local one in the Finchley Road at least twice a week." He said he had no problem endorsing a supermarket. "I am all about making food and cooking fun and tasty. I want to see more organic stuff and more tasty dinners and I want to bring them to ordinary people. I'm not talking about the 50 people who go to farmers' markets, supermarkets are here to stay so I'm happy to work with them and be proactive."

Sainsbury is listening to him, he said. "When we do the ads, it is just a laugh, it's me and the creative team coming up with stuff. The next ad is hysterical, it's got me nan in it."

All Jamie would reveal about the ad, due out in a couple of weeks, is it featured his grandmother, 82-year-old Betty Palmer, and that "I reckon she'll be getting an Equity card after this".

Jamie said he was very impressed by store chief executive Sir Peter Davis, saying: "He has the view that a supermarket has got to offer scope. If you want a £3 bottle of olive oil it is there, but if you want the hand-pressed Tuscan dog's nuts you can get it here too. If you've got £5 or £15 in your pocket you'll get stuff here."

On the issue of supermarkets squeezing British farmers' profits, which Clarissa Dickson Wright had highlighted, Jamie sounded a bit woolly. He said: "I don't know the politics of it but things are changing." Then he added: "Please don't stress me out any more or I'm going to have a heart attack."

He then delighted shoppers by speeding around the store on a new ergonomically designed "bolly trolley" - which has a built-in champagne cooler - yelling: "It's got suspension."