Health warning over Nigella's express turkey

On websites run by the BBC and Channel 4, the TV chef gives advice on preparing the turkey.

She suggests a 6.75kg (about 15lb) bird should be cooked for two hours and 45 minutes at 180c - and blasted at 200c for the first half hour.

But the Food Standards Agency, which is campaigning to prevent Christmas food poisoning, says a bird of that weight should be cooked for three hours and 55 minutes - at 180c.

The discrepancy in cooking time makes it unlikely that Nigella's turkey would be as thoroughly cooked as food health experts recommend.

An FSA spokesman said: "We recommend that a turkey over 6.5kg should be cooked in a preheated oven at 180c for 35 minutes per kg."

There are many different methods of cooking a turkey, it said, but added: "The most important thing is always to check that the bird is properly cooked before serving, because eating undercooked turkey could cause food poisoning."

Miss Lawson's recommended cooking time is very different to those of Delia Smith and Jamie Oliver.

For a 6.5kg bird, Miss Smith suggests a cooking time of four hours and 50 minutes - two hours longer than Miss Lawson's recipe, even though the bird is smaller.

Oliver recommends four hours and 20 minutes in the oven for a 6.5kg bird.

The Quality British Turkey trade body argues for three hours and 30 minutes.

Undercooking shouldn't be a problem for Sainsbury's customers, the supermarket says, as it has included a pop-up timer with all its birds.

The timer has a wax core with a specific melt point and a coiled spring.

The timer is pushed into the deep muscle tissue and, when the turkey has reached the correct temperature, the wax melts, allowing the red part of the timer to pop up.

As the timer senses internal temperature, it eliminates guess work.

Product technologist Ben Hills, said: "Because the timer accurately determines the ideal temperature for cooking and serving poultry, factors like the type of oven you use does not affect the timer's performance."

The FSA says the best way to prevent food poisoning is to ensure turkey is thoroughly cooked for a long time at the correct temperature.

The meat should be piping hot all the way through.

None of it should be pink and any juices run clear.

Miss Lawson's recipe on Channel 4's site advises cooks to poke a skewer into the thigh to ensure that juices run clear.