A ban on junk food advertising on London's public transport network has come into force.

Adverts for products high in fat, salt or sugar, such as sugary drinks, burgers and chocolate bars, will be banned across the London Underground and Overground as well as buses and bus shelters.

Food and drink brands, restaurants, takeaways and delivery services will only be able to place adverts which promote their healthier products, rather than simply publicising brands.

The ban came into effect on Monday after London mayor Sadiq Khan launched a public consultation on the plans in May, saying action was needed to tackle the capital's "ticking time-bomb" of childhood obesity.

A total of 82% of the 1,500 respondents supported the proposals.London has one of the highest child overweight and obesity rates in Europe, with almost 40% of children aged 10 and 11 overweight or obese.

Children from poorer areas of the capital are disproportionately affected, with young people in Barking and Dagenham almost twice as likely to be overweight as children from Richmond.

Similar schemes have been rolled out in a handful of cities around the globe, although health campaigners have often found their proposals met with resistance.

Amsterdam, the Dutch capital, banned junk food advertising at the city's network of metro stations amid concerns over childhood obesity, while a bus company in Canberra, Australia, introduced a similar policy in 2015 as part of a crackdown on advertising.