German hackers' group Chaos Computer Club (CCC) presented its annual satirical Chaos CeBit Award (pictured) at the CeBit IT trade show to Siemens for the company's SmartFilter software. The group said it was honouring Siemens' "special services" in the area of "internet censorship and obstacles to communication".

SmartFilter is a web filtering tool based on a "control list" of website categories and blocked sites. The software is implemented on Siemens' internal servers, and is also available for sale to external customers.

Companies all over Europe, including ones in the UK, are busy installing software like this to prevent staff seeing frowned-on sites.

According to CCC, there is "a certain comedy" to SmartFilter's categorisation of sites. The filter lists the CCC site under "criminal skills", so Siemens employees and others using SmartFilter-equipped browsers or email servers are unable to access the club's domain (www.ccc.de).

CCC said it was particularly troubling that the filter blocks labour unions' web content, but allows industry associations representing employers.

"A filtered internet goes against the basic right to free communication," the group said. "[But] a filter for the internet can always be circumvented [using proxies]." Knowledge such as this is probably why CCC's site is denied by SmartFilter systems.

The prize 'trophy' consists of a plastic coffee filter filled with coloured chocolates. "As with SmartFilter, unfortunately not much comes through at the other end," CCC said.

"We are taking a sportsmanlike view," said a Siemens spokeswoman. "We accept [the award] with humour."