Diseases such as cancer, heart disease and diabetes are some of the biggest health challenges facing the world, experts have said.

The number of new cancer cases worldwide stands at 12 million a year - up a fifth in under a decade.

This is more than four times the annual number of new HIV infections, and 2.8 million of these cancers are linked to poor diet, a lack of exercise and being overweight.

The number of cancers that could potentially be prevented is expected to rise dramatically over the next decade as more people lead sedentary lifestyles and become obese.

The data was released by the World Cancer Research Fund (WCRF), ahead of the United Nations summit on non-communicable diseases (NCDs) later this month. The charity is urging Prime Minister David Cameron to attend to show the UK's commitment to tackling preventable deaths.

Experts also warned against the involvement of food and drink companies in developing health policy. The Government has come under fire from several health charities over its responsibility deal, which aims to form partnerships with produce firms.

Earlier this year, Health Secretary Andrew Lansley offered reassurance to junk food manufacturers, saying he wanted to avoid "intrusive, restrictive and costly regulation".

The Government has been criticised for cutting spending on the Change4Life health campaign in favour of getting commercial companies and charities to fill the gap.

Cadbury, Unilever, Coca-Cola, Kellogg's, Kraft, Mars, Nestle and PepsiCo have all been involved, alongside Britvic and supermarket giant Tesco. Some of the companies have reformulated foods so they contain less sugar, saturated fat or salt.

A spokesman for the Department of Health said: 'This week's responsibility deal calorie labelling announcement shows real progress that can be achieved by working with industry voluntarily to help improve public health, creating an environment that supports people to make informed, balanced choices about their health.'