Billboards advertising junk food from vendors like McDonald's Corp. might be banned from London's Underground rail and bus network under new plans announced by the city's mayor, as part of his efforts to tackle rising levels of childhood obesity.

Sadiq Khan, elected mayor of London in 2016, said in a statement that he wanted to reduce the influence and pressure put on children and families to make unhealthy choices. Nearly 40 percent of 10-11 year-olds in the capital are overweight or obese, one of the highest rates in Europe, the mayor's office said.

A large percentage of the advertising that would be affected comes from "a handful" of major companies and brands, a Transport for London (TfL) spokesman wrote in an email. A spokeswoman for McDonald's, whose advertisements are a regular fixture at London Underground stations, said the company shares the mayor's ambition to reduce childhood obesity.