Hackers, the most maligned species of the digital age, will tonight be declared the ideological heirs to the great protest movements of the 19th and 20th centuries.

Once hacking was regarded as the pastime of attention-grabbing nerds. But a meeting at the Institute of Contemporary Arts in London will be told how credible an activity it has become in the era of direct action. Old-fashioned hacking, the meeting will hear, has given way to hacktivism: a highly politicised underground movement using direct action in cyberspace to attack globalisation and corporate domination of the internet.

"Hacktivists have provided a new political ethic for the hacking activity of the past 'that tended to be more about narcissistic power games than any real protest against the system," said Paul Taylor, a sociology lecturer at Salford university. "Hacktivism can be seen as the latest manifestation of a long history of opposition to capitalism and its disorienting effects."

Targets - mainly multinational corporations and political parties - have been hit with a range of electronic weapons, from viruses to email bombs, which crash websites by bombarding them with thousands of protest messages.

Paul Mobbs of a British hacktivist group, the electrohippies collective, will tell the meeting that the internet "removes the advantages that larger or mainstream groups possess, for example money, influence and preferential access to media. No longer are small minorities restricted by lack of access. On the internet all access is roughly equal."

Companies are spending increasing amounts on protecting their computer systems while governments introduce tougher legislation.

Under the Terrorism Act, which came into power last month, anyone who tries to "seriously disrupt an electronic system" with the intention of threatening or influencing the government or the public, and does it to advance a "political, religious or ideological cause", can be classed as a terrorist.

Another new law, the Regulation of Investigatory Powers Act, gives police and the security services the power to collect internet information without a warrant and to demand the keys to encrypted material.

Useful links

Electrohippies collective
US Cult of the Dead Cow hackers' site
Salford University institute of social research