Google is facing growing pressure over claims it's profiting from hate speech as some of Britain's biggest banks are the latest to pull their ads from YouTube.
Royal Bank of Scotland, HSBC and Lloyds have suspended their advertising with the tech giant following an investigation which revealed household brand names were appearing next to offensive and extremist content on the video site.
A spokesperson for RBS said: "We are not aware of any issue with our ads to date, but we take this issue extremely seriously and are suspending all advertising until they fix this."
Other high-profile brands Vodafone, Sky and Barclays are also considering whether or not to withdraw ads, according to the Sunday Times.
It follows the extraordinary steps taken by french advertising group Havas on Friday, which pulled advertising of all its UK clients on YouTube and Google Display Network.The media agency sells ads on behalf of O2, Royal Mail, the BBC and Dominos.
WPP, the world's biggest advertising group, fell short of pulling its clients' ads. But, chief executive Sir Martin Sorrell warned they "cannot masquerade as technology companies" and have the same responsibilities as any other media company.
Earlier, several brands - The Guardian, Channel 4, L'Oreal and government bodies such as Transport for London (TfL) and the Ministry of Defence (MOD- also withdrew from advertising through the channel.
Google defended its abilities to tackle the problem, saying it invests millions in and employs thousands to stop bad advertising practices, but admitted it doesn't always "get it right".
"Just last year, we removed nearly 2 billion bad ads from our systems, removed over 100,000 publishers from our AdSense program, and prevented ads from serving on over 300 million YouTube videos," said Google UK managing director Ronan Harris in a blog post.
"In a very small percentage of cases, ads appear against content that violates our monetisation policies. We promptly remove the ads in those instances, but we know we can and must do more."
However, the tech firm was hauled in front of the Cabinet Office on Friday to explain itself and will be asked to update civil servants on their actions again next week.
It follows a severe ticking of for Google by MPs on the Home Affairs Select Committee last week, along with Twitter and Facebook. They accused the online channels of failing to do enough to tackle offensive content posted on their platforms with committee chair Yvette Cooper labelling Google's efforts on community standards "a bit of a joke".
She followed this up with a stinging letter to Google's head of public policy Peter Barron accusing the company of profiting from hatred.
The debacle comes ahead of Ad Week Europe, where several senior executives from Google are set to appear on stage with peers to discuss the future of advertising.