Back off Martha! Nigella claims US rival fancies her husband

The TV chef launched a broadside against her American rival, claiming she had a "soft spot" for multi-millionaire art collector Charles Saatchi.

When Lawson became famous in the US, Stewart dismissed her as "what's her name who married the Saatchi".

But in an interview with the Radio Times this week, Lawson said: "I know her, and I suspect she has a soft spot for Charles.

"I'm sorry that even though she's so great and successful she has to disparage someone else. It's not necessary, but everyone has his or her insecurities. You should try to keep them to yourself and behave in a confident way."

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The curvaceous 47-year-old admitted to insecurities about her figure.

"I worry about putting on weight, but clearly not enough. I tell Charles I want to lose this bit and that, and he says, 'Those are the bits I like,' which is great.

She continued: "On a good day, I tell myself, 'Have another doughnut'. But I'm always anxious - why would you get up in the morning if you weren't a bit fearful? Everything is a balance between tedium and fear."

In the interview to promote her new 13-part BBC2 series, Nigella Express, Lawson admitted her 2005 ITV1 chat show was a flop.

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"I knew it wasn't me. On the first show, I was so frightened I thought I'd never come out of my dressing room. I felt awkward and didn't want to hear my voice. It stirred up all the shyness from my childhood," she said.

"I now know I can't ever be a presenter, and won't do scripts."

Elsewhere, Lawson confessed to a love of takeaways and greasy spoons - and revealed she travels everywhere with a tube of Colman's mustard in her handbag.

"I need to take food with me everywhere. The notion of being in a place without it frightens me. I often have a packet of Twiglets in my bag, and always a tube of Colman's mustard," she said.

"Until last year I travelled abroad with a kettle - I didn't like to ring room service for just a cup of tea - but now I realise I can ask them to put a kettle and milk in the room."

Nigella Express will show how to cook meals in minutes.

The TV cook said she doesn't believe people who say they're too busy to make home-cooked food.

"One is aware it's timely because people go everywhere in a hurry, office hours are later, and most families can't get by without both husband and wife working. But I say, rather uncharitably, that everyone insists they're so busy as if they're writing War And Peace in their spare time," she said.