Public health experts have accused the Federal Government of trying to weaken a proposed UN declaration designed to combat obesity.

According to a draft text obtained by ABC's Lateline, Australia is seeking to remove a paragraph which calls for a reduction in salt, sugar and fat from food.

The United Nations will host a summit later this month on the spiralling global health crisis caused by so-called lifestyle diseases including diabetes, cancer, heart attacks and strokes, which are now responsible for two-thirds of the world's deaths.

The summit is supposed to galvanise urgent global action, as happened 10 years ago for HIV/AIDS.

But negotiations to finalise a declaration on what governments should do have been bogged down and public health experts say richer countries like Australia, the US and Europe have squashed efforts to include specific targets such as reducing mortality by 25 per cent by 2025.

Boyd Swinburn from Deakin University says the declaration started strong, with outcomes and targets and accountability mechanisms, but they have since fallen by the wayside.

"Those have all gone and now it's quite a weak, watered down political statement," he said.

The draft UN declaration, dated September 1, calls for countries to implement cost-effective interventions to reduce saturated and trans fats in food, reduce salt and refined sugars in foods, and discourage the production and marketing of unhealthy foods.

But according to the draft, Australia wants that paragraph deleted, as do the US and Canada.

"I think this is a major concern that Australia, along with some of the other wealthy countries like the US and the EU, are seeking to weaken the wording, or in this case, pull out a whole paragraph which refers to the implementation of cost-effective policies to improve the food supply," Mr Swinburn said.

Position 'undermined'

He says developing countries are being devastated by lifestyle diseases, which are responsible for most premature deaths before 60.

"The food industry clearly wants to continue to grow its markets for high-fat, high-sugar foods in developing countries, and this is a little bit in parallel with the tobacco industry," he said.

"Once the clamps come on in the wealthy countries, it shifts to the poorer countries to promote and sell its products."

And Australia's international position appears to be at odds with its own national agenda.

Michael Moore from the Public Health Association Of Australia says the organisation has raised its concerns with the Department of Foreign Affairs.

"What we're concerned about is on the one hand the Government is there establishing the National Preventive Health Agency, looking to deal with obesity, putting a whole lot of effort into it through the Department of Health, [but] on the other hand, through international treaties it's being undermined," he said.

"It just seems that one hand of government's got no idea about what the other hand of government's doing."

A spokesman for Health Minister Nicola Roxon said the Government could not comment on the negotiations, but said it was a world leader in combating smoking and that it wanted the strongest possible outcome from the UN summit.

And a spokesman for the Australian Food and Grocery Council says industry is working with government to reduce salt, sugar and fat in processed food.