The social network also removed eight posts from its site this week after The Telegraph was able to easily find content encouraging violence linked to the US election result.
One post, in which an American Facebook user said she wanted to see Nancy Pelosi's "blood gushing", was found in just three clicks. Another post, found on Facebook in minutes, encouraged further violence in Washington DC. "I strongly support burning Capitol Hill to the ground," wrote one right wing Facebook user.
A Facebook spokesman confirmed that the posts had been deleted. "We have strict policies against inciting violence and these rules apply across Facebook, including in groups. Our teams are working 24/7 to find and remove this type of content," he said.
Facebook's lack of action has caused some companies to maintain their ad freeze since last year, with outlays for Coca-Cola, Electronic Arts and JP Morgan Chase remaining well below their 2020 levels as of January 12.
Others, such as Nike, Procter and Gamble, L'Oreal and Kellogg, appear to have dramatically reduced their spending on both Facebook and Instagram just this week, raising the possibility of a renewed boycott campaign.
The activist group behind last summer's boycott this month told the Telegraph that it would "double down" on pressuring advertisers to pull their money from the embattled social media giant.
William Merchan, Pathmatics' chief revenue officer, said that companies pulling their money probably did so in order to avoid appearing insensitive or having their brands tainted when their adverts appeared alongside unsavoury or traumatic content.
Mr Merchan said: "At the beginning of the year, you do typically see a pullback on budgets from some brands after they've had their big push for the holidays.
"But in some examples, there probably was a pullback in reaction to the events... if you're on the buying side, you're going to have a second look and say, 'OK, does it make sense to continue my ad promoting the new Nissan vehicle when this stream is filled with horrific images and speech that does not put people in the mood to click to connect with a dealer?'"
More than 1,000 companies heeded the call of US civil rights activists last June to pull their money out of Facebook. Pathmatics' data shows that many have kept up their boycotts, meaning that spending by Facebook's top 100 advertisers was already lower than last year, despite the pandemic.
After the attack on the Capitol, many companies also cut their spending on Amazon, Twitter and YouTube, but the difference was most pronounced on Facebook.
A spokeswoman for Coca-Cola said: "While we don't disclose details on our marketing spend, Coca-Cola uses social listening as a tool to gauge sentiment online to determine the right time to engage or not engage with our consumers.
"When it is necessary, the company and our brands observe some level of social silence. With such an unprecedented 2020 and start to 2021, we've had to observe social silence at a much greater rate than previous years."
Nissan and American Express said that they temporarily pause spending when major events make it hard to reach their consumers. Paypal and Microsoft likewise reduce their online advertising during crises, it is understood. Other companies' motivation was unclear.
Conversely, some advertisers appear to have increased their spending on YouTube during the chaos. Mr Merchan suggested that the video streaming sight had become a beneficiary of a massive spike in views for reputable news networks, whose advertising slots are precious and usually scarce.
- Telegraph Media Group
