The Queensland Government will ban junk food promotions at government-owned sites in a bid to crack down on poor diets and childhood obesity.

Key points: Health Minister Steven Miles says obesity is a real challenge for Queenslanders

Health Minister Steven Miles says obesity is a real challenge for Queenslanders The ad ban has been welcomed by the Obesity Policy Coalition

The ad ban has been welcomed by the Obesity Policy Coalition The State Opposition is branding the move a "knee-jerk reaction"

Health Minister Steven Miles said the unhealthy marketing would be phased out at more than 2,000 outdoor advertising spaces, including bus stops, train stations and road corridors.

"Junk food advertisers target kids, we know that, and obesity in childhood is a leading indicator of obesity in adulthood," Mr Miles said.

"This is about doing what we can to protect our kids from the kind of marketing that leads them to make unhealthy choices."

Mr Miles said the ban would affect leased spaces owned by the State Government.

"Obesity is a real challenge for our community, for our hospitals and the health services, but also for the individuals who are suffering — this is really just a decision about the Government leading by example and saying that we will use our spaces to advertise healthier options," he said.

Obesity Policy Coalition executive manager Jane Martin said the restrictions were a win for young people and their health.

"This is exactly the sort of action that's recommended by agencies around the world, like the World Health Organisation, to protect children from the influence of junk food marketing," Ms Martin said.

"Young people use public transport, they're exposed to this sort of marketing, it's wallpaper in their lives.

"This is a really important step to protect children when they're on their way to school, going to meet up with friends [where] it's very difficult for parents or anyone else to intervene."

Ms Martin said Queensland would join the ACT in providing the lead for other jurisdictions considering similar reform.

She said other areas of concern, including digital and television marketing, were in the remit of the Federal Government.

'Focus on hospital beds, not billboards'

Deputy Opposition Leader Tim Mander described the ban as a "knee-jerk reaction" by the Government to "deflect attention away from the current health crisis".

"We think the Government should be focusing on hospital beds, not billboards," Mr Mander said.

Mr Miles said it could take a few years to phase out the ads. ( ABC News )

"If it was fair dinkum, it would not have reduced the preventative health budget by $300,000.

"These are items that are freely available in the community and people need to make their own choices.

"They need to be educated appropriately [and it] raises questions of how far do you go?"

Mr Miles said the ban would not apply to advertising space in stadiums because those contracts were "much more complicated".

"This is a chance for us to prove that it can work in places where the contracts are much simpler," he said.

"The approximation of the current level of revenue is in the millions of dollars.

"Of course, that won't all be lost revenue — some of that advertising space would be taken up by other advertisers, hopefully other people advertising healthier food choices."

The Minister also acknowledged it could take a few years to phase out junk food ads completely.