Julian Assange, the founder of whistleblower website WikiLeaks, has warned that the internet was the "greatest spying machine the world has ever seen" and an obstacle to free speech.

Speaking to students at Britain's prestigious Cambridge University, the former computer hacker claimed that the internet, particularly social networking sites such as Facebook, gave governments greater scope for snooping.

"There was actually a Facebook revolt in Cairo three or four years ago," Assange explained.

"It was very small... After it, Facebook was used to round up all the principal participants and they were then beaten, interrogated and incarcerated.

"So while the Internet has in some ways an ability to let us know to an unprecedented level what government is doing... it is also the greatest spying machine the world has ever seen," he added.

The rise of technology was helping tyrannical regimes, said the 39-year-old Australian, who is currently fighting extradition to Sweden over allegations of sex offences.

"It is not a technology that favours freedom of speech," he claimed.

"It is not a technology that favours human rights.

Rather it is a technology that can be used to set up a totalitarian spying regime, the likes of which we have never seen."

But the activist restated his belief that his website had helped trigger the ongoing Arab uprising.

He also said the release of official US diplomatic documents had "changed part of the dynamics" in Tunisia, resulting in eventual regime change.

Assange sympathised with imprisoned US soldier Bradley Manning, who is suspected of having leaked the cables.

"Our support for his plight cannot be stated too loudly," he said.