BEIJING, March 28 (Kyodo) — North Korea has restricted a newly started mobile Internet service to long-term visitors and foreign residents, making it no longer possible for tourists to surf the Internet from their cell phones and other mobile devices, the Pyongyang-based service operator said Thursday.

Koryolink, a North Korean-Egyptian joint venture that operates the mobile phone service in the country, did not say why authorities in Pyongyang no longer allow tourists to use the service, which was launched Feb. 25.

North Korea watchers speculate the authorities may have found it impossible to control an increased flow of information from the country to the outside world, especially the postings on Internet sites of photographs of military-related or other sensitive objects that they would not want to be made public.

A Koryolink employee said the mobile Internet service remains available for foreign residents in North Korea, but that "short-term" visitors can no longer subscribe to the service.

An informed source in Beijing said Koryolink informed travel agencies in China and elsewhere last week of the North Korean government's decision to restrict the service.

But the source said Koryolink appears to continue offering the service to tour guides and others who frequently visit North Korea even though they are not technically "long-term" visitors.

Fearing that an unrestricted flow of information from abroad could have a destabilizing impact, North Korean authorities strictly control the public's access to the Internet. Locals only have access to a domestic intranet.

North Korea has more than 1.5 million mobile phone subscribers, but locals cannot make international calls. Similarly, locals cannot call foreign visitors and residents in North Korea -- and vice versa -- as the systems have different settings.