The deal is being trumpeted as an enjoyable way to lose weight, but nutritionists have criticised it as a marketing ploy that doesn't promote healthy eating.

As part of the deal - which the company says is the first of its kind in the world - McDonald's will use the Weight Watchers logo on its menu boards and Weight Watchers will promote McDonald's to dieters.

Several items on the fast food giant's menu - the Filet-O-Fish, Chicken McNuggets and Sweet Chilli Seared Chicken Wrap - have been approved for the Weight Watchers programme. Each meal is worth 6.5 points on the programme, which assigns points to food items and allows dieters to consume 18 to 40 points each day to achieve their goal weight.

Chris Stirk, Weight Watchers director of business in Australia and New Zealand, said the partnership between the two companies reflects "part of our philosophy that you can enjoy life ... while still achieving your weight loss goals."

But nutritionists and obesity experts said the menu items are merely a marketing ploy to lure customers into the restaurant.

"It's all about sales really," Australian Obesity Policy Coalition senior adviser Jane Martin said. "It implies this food is healthy ... when often it is high in fat and salt. Chicken McNuggets are Chicken McNuggets whether its got Weight Watchers on it or not."

Mark Hawthorne, chief executive officer of McDonald's New Zealand, said the country was the only one to have a McDonald's that offered Weight Watchers meals. McDonald's New Zealand has "no knowledge of any plans to roll this out in other countries," spokeswoman Kylie Taylor said.

The fast-food chain, widely criticised for selling a high-calorie, high-fat menu that includes super-size meals, was "making every best effort to generate a change in behaviour, to create an awareness in consumers about making healthy choices," Hawthorne said.

McDonalds has made changes to its menu, adding healthier products such as entree-sized salads, fruit and grilled chicken sandwiches.