The "Defacer's Challenge" got off to a quick start yesterday with 300 attacks reported minutes after the 6.00 a.m. official start, said Mr Roberto Preatoni, founder of Estonia-based Zone-H.org, a site that tracks hack attacks.

"There were no big names," he said. But he added that his own site, www.zone-h.org, was knocked offline for much of the day because of a high volume of legitimate visitors and apparent attempts by hackers to bog down his computer servers.

According to the contest website www.defacers-challenge.com, which was taken offline last week, hackers were urged to prove their skills by defacing as many websites as possible during a six-hour period yesterday.

Points were awarded for the number and type of computer servers they infiltrated, the rules stated.

Concern grew among cyber security organisations last week that the competition would cripple countless websites but by yesterday afternoon, as the event was drawing to a close, there was no sign of damage among the Web's most popular sites.

The internet's largest websites, including Amazon.com and Yahoo.com, were functioning as normal.

"It seems to be a damp squib," said Mr Graham Cluley, spokesman for UK-based security firm Sophos.

Via.Networks, a US-Dutch internet service provider and website hosting firm that manages websites for more than 50,000 clients in the US and western Europe, also reported no incidents.

"None of our customers have called to report any problems. It's all quiet on the western front," said Ms Joanne Hughes, a spokeswoman for Via.Networks.

Hacking activities have been increasing for years as the expertise behind compromising a website's vulnerable computer server is freely passed around the internet in chat areas and is posted on websites dedicated to the activity.

Hacker attacks range from outright defacement to flooding a server with data requests, thereby knocking the site offline.

In the former case, hackers replace the contents of a Web page with their own messages, often a political rant written in the signature style of broken English.

With hackers sending out challenges regularly, security officials expressed bewilderment that this contest received so much press attention, fearing it would only encourage more elaborate events in the future.

But Via.Network's Ms Hughes saw something of a silver lining in the fact that she and her team were on the ready this weekend for a possible showdown with hackers.

"If it makes people more aware about security, then that's a good thing," she said.