"Hate speech and fake news threaten to undermine the principles of respect and trust that bind communities together," said Vodafone group chief Vittorio Colao as he restated the company's commitment to diversity and inclusion.
"We also greatly value the integrity of the democratic processes and institutions that are often the targets of purveyors of fake news," he added. "We will not tolerate our brand being associated with this kind of abusive and damaging content."
The detail of the new approach – which has a potentially major impact as around half of Vodafone's £750m global advertising budget is spent on digital ads – involves working with Google and Facebook as well as agencies to build a whitelist.
"It is relatively easy to blacklist certain sites, such as those relating to porn and gambling, but it is difficult to exclude content that is – in editorial terms – at odds with an advertiser's own principles and beliefs," observed Matt Peacock, group director of corporate affairs at Vodafone.
"When it comes to making a judgment about a site or channel focused on fake news or hate speech, what's needed is a human judgment, an editorial assessment," he told the Guardian. "It's not possible to rely on algorithms alone. For that reason, we've concluded that the best way to ensure brand safety is to use a whitelist approach."
The list will be reviewed regularly to ensure it is "appropriate and neither too broad nor too narrow".
It will not include tabloid news sites whose content can sometimes breach the guidelines, instead focusing only on those sites whose "predominant purpose" is fake news that sets out to intentionally mislead or hate speech – including those sites that "deliberately intend to degrade women or vulnerable minorities".
A Vodafone source told the Telegraph that the new policy partly signalled "a return to the old days, where we know the publications that are going to be hosting our brand" – a development that major news publishers, who have been losing ad revenue to Google and Facebook, will welcome.
Data sourced from The Drum, Guardian, Telegraph; additional content by WARC staff