Reuters news agency says the websites of entities including major media outlets became temporarily unavailable on Tuesday.
The agency reported that the widespread outage hit organizations across the world, including the New York Times and the Financial Times, as well as the British government.
Reuters said some reports pointed to a glitch at US-based cloud service company Fastly's network service.
Fastly posted on its website at around 10:00 UTC on Tuesday that it was investigating the issue.
The firm then said about one hour later that "the issue has been identified and a fix has been applied."
Fastly's Japan office says the outage was caused by technical problems and had nothing to do with cyberattacks.