Facebook’s main apps suffered a widespread outage for at least six hours on Monday, cutting off access for people around the world to some of the internet’s most widely used services.

The worst disruption to hit the social networking company for more than two years brought a wave of criticism online, and came as Facebook was already facing a backlash over claims from a whistleblower that the company had deliberately turned a blind eye to the spread of disinformation and other adverse effects from its network.

Frances Haugen, a product manager who left the company earlier this year, was due to testify at a Senate hearing on Tuesday. She plans to urge lawmakers to regulate the social media group more tightly, likening it to tobacco companies who hid the dangers of smoking, opioid makers, and carmakers before seat belts became mandatory, according to written remarks.

Facebook’s network problems began suddenly at around 11.30am on the east coast of the US, when users found they couldn’t view or post on the main Facebook and Instagram apps, send messages through the Messenger and WhatsApp services, or reach the website of the virtual reality service Oculus.

“It was as if someone had ‘pulled the cables’ from their data centres all at once and disconnected them from the internet,” the internet infrastructure company Clouflare said in a blog post later in the day.

Facebook later apologised for what it said had been a “faulty configuration change” on its network, which had interrupted traffic flowing between its data centres and caused a “cascading effect”, bringing services to a halt.

The disruption also hit “internal tools and systems we use in our day-to-day operations, complicating our attempts to quickly diagnose and resolve the problem”, said Santosh Janardhan, vice-president of infrastructure.

Facebook’s shares closed 4.9 per cent lower on Monday, taking the total decline over the past month to 15 per cent.

The company’s shares have also come under pressure over worries that changes to Apple’s privacy rules will limit the data it can collect for advertising purposes. Wall Street has also grown increasingly concerned about the threat of regulation.

Cyber security experts said the failure appeared to have been caused by a problem in the DNS, the global directory that matches the internet addresses users enter with the domains they are trying to access — a central part of the system for routing online traffic.

Some users trying to access the company’s various websites received a “5xx server error” warning, a standard message returned to internet users when a server is unable to perform the task that’s been requested.

Jack Dorsey, Twitter’s chief executive, joined in the social media pile-on against Facebook as the outage continued. In response to a tweet from the whistleblower Edward Snowden, who used the outage to advise people to switch to the messaging service Signal, Dorsey tweeted: “Signal is WhatsUp”.

Criticism of the company is set to resume on Tuesday, with Haugen, the Facebook whistleblower, set to make her first appearance on Capitol Hill.

“When we realised tobacco companies were hiding the harms it caused, the government took action,” she said in written remarks published ahead of the hearing on Tuesday.

She added: “When we figured out cars were safer with seat belts, the government took action. And today, the government is taking action against companies that hid evidence on opioids. I implore you to do the same here.”

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