While the average hacker might once have been a mischievous teenager or cybercrook, today's Internet attackers are increasingly likely to be state-sponsored or fighting for political goals, experts said.

Attacks against Internet giant Google and other firms -- blamed on China-based cyber spies -- have raised fresh questions about the role of governments in web warfare.

Google said Tuesday it would no longer censor search engine results in China and possibly pull out of the lucrative market, complaining about "highly sophisticated" cyber attacks aimed at Chinese human rights activists.

China-based cyber warriors struck the Internet giant and reportedly more than 30 other unidentified firms in an apparent bid for computer source codes, intellectual property, and information about activists around the world.

Given the targets, the hackers appeared to be attempting to gain information relating to specific individuals, said Paul Craig, principal security consultant at Security-Assessment.com, an advisory firm in New Zealand.

"This does raise the possibility of a government sponsored attack against individuals, or a commercially sponsored attack," he said.

"Typically, the online criminal hacker is attempting to steal intellectual property, financial information, or money. This does not seem to be the motive in this case," he said.

Chinese hackers are notoriously patriotic and were blamed for past cyber attacks on the website of Tokyo's Yasukuni war shrine, seen by many Asian nations as a symbol of Japan's past war-time aggression.

Google said its investigation revealed that accounts of China human rights activists who use its free email service in Europe, China or the United States have been "routinely accessed" using malware sneaked on to their computers.

The Internet giant did not specifically accuse the Chinese government of being behind the cyber attacks, but China is seen as the probable culprit due to the sophistication of the attacks, the targets, and the fact the assaults originated in that region.

"It is always difficult to prove that any particular event is related to state-sponsored hacking," Chester Wisniewski, a senior security adviser at Internet security firm Sophos, wrote in his blog.

"It is clear that Google feels it has very strong evidence that this is the case or it would not disclose publicly such an attack. The dramatic change in stance could signal a trend for other companies who were allegedly victimised by the same attackers," he added.

Some industry watchers said the hackers in the Google case might not have been politically motivated.

"In general, Internet users in China are young people. Many of them are teenagers. They might organise attacks but often for very childish reasons," said Masaki Ishiguro, a senior researcher at the Mitsubishi Research Institute.

"Politics or issues of freedom of speech might just serve as a reason or a trigger for young people to stage attacks," he said.

One thing is sure: cyber attacks are becoming increasingly sophisticated. In July of last year the White House, State Department and Pentagon websites were targeted in a coordinated cyber attack that also crippled sites in South Korea.

South Korea blamed the attacks on North Korea.

"Cyber attacks have become large-scale and highly-organised," said Judy Wu, research manager at consulting firm IDC Asia Pacific in Hong Kong.

While hacking technologies are now easily accessible on the Internet, "many of the cyber attacks are certainly state-sponsored," she said.

State-backed attacks used to target governments or defence agencies, but are also now apparently being directed at large corporations, she said.

There have been a growing number of reports of cyber attacks and network infiltrations apparently linked to the political goals of regimes, IT security firm McAfee Inc. noted in its Virtual Criminology Report 2009.

"While we have not yet seen a 'hot' cyber war between major powers, the efforts of nation states to build increasingly sophisticated cyber attacks capabilities, and in some cases demonstrate a willingness to use them, suggest that a 'Cyber Cold War' may already have begun," it warned.