Jamie Oliver's restaurant chain Fifteen, which has a branch in Melbourne, has come under fire from one of Britain's most outspoken chefs.

Clarissa Dickson, one half of the famous cooks in the Two Fat Ladies TV series, says she is afraid to dine at Oliver's restaurants.

"He is a brilliant cook," The Independent on Sunday newspaper quoted her as saying.

"But his restaurants are lacklustre, I'm told.

"I don't know. I don't eat in them. I don't want to risk being poisoned."

The two TV chefs have had a long-running feud, with Dickson accusing Oliver of "selling out" when he agreed to star in advertisements for British supermarket giant Sainsbury's.

As well as Melbourne, Oliver has branches of Fifteen in London, Newquay, south-west England and in Amsterdam.

The TV chef set up the chain as a way of helping disadvantaged young people get jobs in the restaurant industry.

A spokesman for Oliver said diners had nothing to fear from his restaurants.

"Clarissa has no fear of being poisoned ... because I suspect none of our restaurants would welcome her, for fear of offending the other guests," he said.