At the time of launch Orascom said it planned to invest about $400m in the North Korean mobile network, beginning in the capital, Pyongyang, and rolling out the service across the country.

The service is restricted to government approved customers with handsets costing around $700 each, putting them well beyond the reach of all but a very few North Koreans.

According to recent reports the number of subscribers to the new service had hit 20,000 by the end of March, and was continuing to grow.

'Black hole'

North Korea is one of the few countries in the world where internet access is virtually non-existent.

Reporters Without Borders, the Paris-based anti-censorship body, has dubbed North Korea the world's number one "internet black hole".

The country's designated domain suffix ".kp" is largely unused, although a handful of senior officials and government departments are believed to have internet access via a pipeline into China.

Kim Jong-il, the North Korean leader, is believed to frequently browse the web through his own connection.