The hacktivists named and shamed the firm as CloudFlare, dubbing them "shameful" on Twitter
A trendy Silicon Valley business has been accused of aiding Islamic extremists as they suffer a wave of hack attacks from Anonymous activists.
Members of Anonymous have taken to social media to accuse CloudFlare of protecting ISIS websites.
The hacking organisation declared war on ISIS following the Paris terror attacks earlier this month, when 130 innocent people were murdered.
CloudFlare provides services to defend against hacks and speed up internet loading times.
One service it offers its estimated four million customers is preventing Denial of Service Attacks - a tactic used by hackers that overruns sites with traffic.
Accusations: CloudFlare has said that their website falls under free speech
That hacking method can shut sites down, however CloudFlare's services are being allegedly used by 40 terror sites which mainly publish propaganda.
One account linked to Anonymous shared its frustration that CloudFlare's services were being exploited by Islamic extremists.
The account posted on Twitter: "Once again, @CloudFlare have been found to be providing services to pro-#IslamicState websites. Shameful."
But the firm has defended itself from critics, dubbing the claims from Anonymous activists as "armchair analysis".
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Speaking to the Register, Matthew Prince, CloudFlare's cofounder and CEO, said: "I'd suggest this was armchair analysis by kids – it's hard to take seriously.
"Anonymous uses us for some of its sites, despite pressure from some quarters for us to take Anonymous sites offline.
"Even if we were hosting sites for ISIS, it wouldn't be of any use to us,' Prince added.
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"I should imagine those kinds of people pay with stolen credit cards and so that's a negative for us."
However Twitter users are still criticising the company.
It is not the first time that CloudFlare's services have been criticised. In 2013 it was claimed that Al Qaeda were exploiting their services.
Mr Prince also defended CloudFlare in a blog post.
He wrote: "A website is speech. It is not a bomb.
"There is no imminent danger it creates and no provider has an affirmative obligation to monitor and make determinations about the theoretically harmful nature of speech a site may contain.
"If we were to receive a valid court order that compelled us to not provide service to a customer then we would comply with that court order.
We have never received a request to terminate the site in question from any law enforcement authority, let alone a valid order from a court."