Celebrities and sports personalities should not be allowed to advertise unhealthy food, a leading medical journal has said.

The Lancet said in an editorial that celebrity endorsement of unhealthy food should be banned and called for legislation to regulate the "junk food" industry, reported Reuters.

The journal criticised the BBC for franchising its Tweenies children's TV characters to fastfood giant McDonald's. It also slammed the government for allowing confectionery giant Cadbury Schweppes to launch its Get Active campaign, in which children can collect chocolate wrappers to exchange them for sports equipment.

Legislation should be introduced to regulate the production of unhealthy food, the journal said.

"Food needs clear, probably iconic, labelling for its nutritional content - an icon for junk food should be easy to design," the article said, as quoted by Reuters.  

Earlier this week, UK health experts warned that obesity was a time bomb waiting to explode and that life expectancy would go down for the first time in decades because of it.