North Korea’s main official news services, its Foreign Ministry, and the Air Koryo national airline were among websites inaccessible on Saturday, before they started coming back slowly around midday according to checks by Reuters.

North Korea’s entire internet infrastructure was not showing up on systems that can monitor internet activities, and email services were also affected, Junade Ali, a UK-based researcher who monitors the North Korean internet, said earlier.

“Hard to say if this is intentional or accidental – but seems like this is internal rather than an attack.”

Officials at South Korea’s cyber terror response centre, a police division that monitors North Korea’s cyber activities, could not be reached for comment.

Martyn Williams, who specializes in North Korea’s technology and infrastructure at the Washington-based Stimson Center, also said the cause appeared to be internal as the Chinese and Russian connections were not working.

North Korea has one of the world’s most strictly controlled internet systems, including access to any form of online communication.

The general public has access only to an intranet set up by the government and that is not connected to the wider global network.

An elite few in the government and leadership are allowed open internet access, and government and news websites often serve up propaganda for outside audiences.

North Korea has in previous years experienced large internet outages suspected as being caused by cyberattacks.

The country operates elite teams of hackers, including a group known as Lazarus run by the government intelligence apparatus, that are blamed for attacks against foreign institutions and companies and more recently for theft and the laundering of cryptocurrencies.

North Korea denies involvement in hacking, crypto thefts and other cybercrime.-Agencies