The growing surveillance and censorship of the Internet "threatens the future of democracy", the inventor of the world wide web said on Friday.

Tim Berners-Lee was speaking at the launch of his World Wide Web Foundation's second annual index measuring the Internet's contribution to social, economic and political development and human rights.

"One of the most encouraging findings of this year's Web Index is how the web and social media are increasingly spurring people to organise, take action and try to expose wrongdoing in every region of the world," said Berners-Lee.

In 80 percent of the 81 countries surveyed, the Internet and social media played a role in public mobilisation in the last year, the foundation said.

"But some governments are threatened by this, and a growing tide of surveillance and censorship now threatens the future of democracy," Berners-Lee said.

"Bold steps are needed now to protect our fundamental rights to privacy and freedom of opinion and association online."

Developing countries are most likely to block and filter online communications, but leaks from fugitive US analyst Edward Snowden revealed that developed countries are more likely to spy on the web, the foundation said.

China, Russia, Saudi Arabia and Pakistan are among the worst offenders for censoring politically-sensitive web content and having inadequate safeguards against government surveillance, the report said.

But the United States, Canada, Britain, Australia, New Zealand and India were listed alongside Mali, Yemen and Kenya as having "inadequate" safeguards against government spying.

Sweden topped the overall Web Index for developed countries for the second year running, largely because of the widespread penetration of broadband, followed by Norway, Britain, the United States and New Zealand.

Mexico topped the list of emerging market countries, followed by Colombia, Brazil, Costa Rica and South Africa, while the Philippines was number one among developing nations followed by Indonesia, Kenya, Morocco and Ghana.