Chinese officials are calling for a mass migration to IPv6 after disclosing that they have only 830 days' worth of IPv4 resources left.

The disclosure was made by Li Kai, director of IP of the China Internet Network Information Center.

Li explained at a conference that, without a rapid changeover to IPv6, internet users in China will start having problems getting online.

"We held seminars almost everywhere to tell operators to apply for the remaining IP addresses as soon as possible, and to prepare the new IP addresses from IPv6 for internet users," he said, according to state media.

Around 80 per cent of China's IPv4 resources have now been taken up. The country's IP allocation recently exceeded Japan's, making it the second largest in the world behind the US.

Li warned that China risked falling behind the US, which already had a well developed IPv6 network. By contrast only Chinese educational establishments are using IPv6.

IPv4 was the first internet protocol to be widely deployed and uses 32-bit addresses, allowing over 4.2 billion individual devices to get online.

This was thought to be plenty in the 1980s but, with more and more devices becoming internet enabled, the supply will run out by 2010 and maybe sooner.

However, Li's estimate of the readiness of the West for IPv6 may be overstating the case.

Vint Cerf, chief internet evangelist at Google, has warned that ISPs are failing in their duty to inform customers of the coming switchover.

"They are persisting in the 'nobody is asking for this' mentality, and are not valuing business continuity as they should," he told The Times.

"When they finally wake up, there is going to be a mad scramble for IPv6 and they won't implement it properly."