Fast food giant McDonald's is to give away free music downloads after teaming up with Sony's music service Connect.
McDonalds is exploring new ways to attract customers
The chain will let customers access one free song from the Connect online music service for every promotional Big Mac meal purchased.
The scheme is launched in the US, Canada and Puerto Rico this month, and in France, Germany and the UK in July.
But the British Dietetic Foundation told BBC News Online the promotional campaign was of a "major concern".
Amanda Wynne of the British Dietetic Foundation, which promotes healthy eating, said: "Children will be one of the target markets, if they are offering free music downloads. It's of great concern and we do need to look at it quite closely."
The UK government recently faced calls to ban junk food ads in the UK in an effort to tackle rising rates of obesity.
And a report for the Food Standards Agency, published in September, concluded there was a link between advertising and children's diets.
Culture Secretary Tessa Jowell asked the television regulator Ofcom to investigate.
Sony's Connect download service was launched in the US in May, offering more than 500,000 tracks for sale.
Justin Timberlake will advertise McDonald's music promotion
"Music continues to be at the forefront of our leadership marketing strategy," said McDonald's marketing chief Larry Light.
Singer Justin Timberlake is set to promote the Big Mac Meal Tracks offer in a television advertising campaign.