MasterChef Australia producers have defended their decision to allow several eliminated contestants back into the competition.

Fan favourite Justine, Tom and Poh are returning to the program in what some have described as a grab for ratings.

Judge George Calombaris has dismissed claims the shock returns are a ratings ploy or designed to alter the outcome of the show, the Herald Sun reports.

"I'm the biggest one for giving people a second chance - it's only fair," Calombaris said.

"They made one mistake and they're out the door. For me, that's pretty unfair. I feel sorry for them.

"It's got to do with the Aussie spirit.

"It's like Ben Cousins - you've made a few mistakes, let's let you play again, go and watch you at the MCG and fill the thing out."

It is a move that will shock viewers who have praised MasterChef for not stooping to the sort of contestant manipulation that regularly occurs on reality shows such as The Biggest Loser.

Calombaris insisted the surprise returns did not upset the four contestants who weathered untold challenges to stay in the show.

"They took it quite well once we explained (our reasons) to them," Calombaris said.

"The decision we made to bring these contestants back wasn't taken lightly."

The returning contestants returned to the show to mix it with diehards Chris Badenoch, Andre Ursini, Sam Caravolo and Julie Goodwin to cook for sailors aboard HMAS Kanimbla.

"At the end of the day, they (viewers) have to trust us," said Calombaris, who made the decision with fellow judges Gary Mehigan and Matt Preston.

Calombaris rated Justine as one of his favourites to win and admits he was floored when she was sent packing in Hong Kong last week.

"I was pretty upset that day when she was out," he said.

"It was a stir-fry and not her thing. If you threw me into an Asian kitchen I'd go down like a sack because it's not my thing and I've been cooking for longer than she has."