In an unprecedented move, Vietnam has called on all companies doing business in the country to stop advertising on Facebook, YouTube and other social media networks in an attempt to combat what they call "toxic" anti-government media.
A spokesman for Prime Minister Theresa May said Google would be attending a meeting at the Cabinet Office later on Friday after the Times newspaper reported that public sector adverts were appearing alongside videos carrying homophobic and anti-semitic messages.
The dodgy advertising placement was spotted by The Times, which found government ads running alongside YouTube videos of a hate preacher banned in the United Kingdom, rape apologists, anti-Semites and white nationalists in the US.
Adverts for big names including Mercedes-Benz, Waitrose and Marie Curie were featured before videos uploaded by ISIS supporters and other terrorist sympathisers, the investigation found.
Havas, whose clients include O2, the telecoms group, the BBC and Royal Mail, said it pulled its ads because Google was "unable to provide specific reassurances. that their video or display content is classified [ as acceptable] either quickly enough or with the correct filters".
Analysis by The Times showed that blacklists which are created to prevent digital adverts from popping up next to extremist content, are not working. The British government also found its ads running next to inappropriate content and has summoned Google to address the British Cabinet Office about the issue.
The Guardian was one of the first to announce on Thursday that it was withdrawing all of its advertising from Google and YouTube after ads promoting its membership program appeared next to "extremist material", including YouTube videos of American white nationalists, a hate preacher banned in the United Kingdom, and a controversial Islamist preacher.
Harris said 400 hours of video was uploaded to YouTube every minute, adding that previous year Google removed almost two billion "bad ads" from its systems, removed over 100,000 publishers from its AdSense programme and prevented adverts from serving on over 300m YouTube videos. The company said that it has started a thorough review of the ad policies and brand controls, and they will be making changes in the coming weeks.
American tech companies are facing tight scrutiny in Europe over their ineffective regulation of hateful and inappropriate content online, and Google is no exception.
The internet giant said it had "strict guidelines" about the placement of adverts but conceded "we don't always get it right".
"You have to take responsibility for this as a media company", the WPP executive said.
In January, Google reported that in 2016 it removed almost 2 billion "bad ads" from its systems, which the company said included self-clicking and fraudulent ads or promotions for illegal products.
It is therefore vital that Google, DoubleClick and YouTube uphold the highest standards in terms of openness, transparency, and measures to avoid advertising fraud and misplacement in the future.