The Chinese regulator has declared Internet phone services other than those provided by China Telecom and China Unicom as illegal, which is expected to make services like Skype unavailable in the country.

The decision was criticized as a measure to protect the duopoly of state-owned telecom carriers, media reports said yesterday.

The Ministry of Industry and Information Technology said all VoIP (voice over Internet protocol) phone services are illegal on the Chinese mainland, except those provided by telecommunications carriers China Telecom and China Uniom. The ministry gave no timetable on when the ruling takes effect.

VoIP is an Internet-based service that helps people save on phone calls. For example, a call to Japan or South Korea costs about 3.99 yuan (60 US cents) a minute, compared with 10 US cents a minute or even free for Skype users.

The decision is expected to make Skype, UUCall and other similar services unavailable in China.

"It's ridiculous," said Kan Kaili, a professor at Beijing University of Posts and Telecommunications. "VoIP is a popular technology worldwide."

Skype was not available to comment yesterday.

The ruling is designed to protect the state-owned carriers, a Xinhua report said.