Leaping the wall; censorship in China.(Internet censorship in China)

Authorities with the jitters

"THE Klingon Empire scored a couple [of] solid hits on the USS Enterprise." So wrote the chief executive of WiTopia to clients in China. The firm provides ways of bypassing blocks imposed by internet firewalls. Like others that help people in China escape internet censorship, it has recently found its services disrupted by what looks like a new kind of attack by China's censors.

Since the Arab awakening, officials have gone to lengths to stop dissidents from trying to foment similar unrest at home. Controls on people attempting to "leap the wall", as internet users describe the process of evading their censors' firewall, have got tighter. Google's e-mail service, Gmail, popular as a way of communicating without interference by keyword-sniffing filters, has also been targeted.

It marks a change of tactic by China's internet police. For years they have largely turned a blind eye to paid-for services, such as WiTopia's, which provide virtual private networks (VPNs) enabling encrypted connections to the many websites blocked by the firewall. Such VPNs are mainly used by foreigners in China, less likely to be trouble-stirrers. (Fee-free VPNs are routinely blocked.) Gmail and other non-Chinese e-mail providers have also been largely left alone. Completely blocking Gmail would raise an uproar, not least among the many foreigners in China. China dislikes being demonised abroad as a draconian internet censor. It denies disrupting Gmail.

China's new tactic, as far as experts can guess, is to make the use of Gmail and paid-for VPN services more inconvenient, but not to cut off access altogether. Google says the government is disrupting its e-mail service, while making it look as if the problem lies with Gmail. Users in China are having intermittent problems accessing the Gmail service.

VPN access has also become hit-and-miss. Some users of their own companies' VPNs, used for secure communications within corporate networks, report similar problems, says Duncan Clark of BDA China, a consultancy in Beijing. For foreign businessmen "it does make you feel much more that there is a cost of being here", he says. Chinese officials, in a state of heightened jitteriness, appear less concerned about foreign whingeing.