Amnesty International has accused technology firms of hypocrisy for their stance on helping authorities around the world to censor the internet.

The human rights organisation has alleged that Cisco, Google, Microsoft and Yahoo are "colluding" in aiding repressive governments around the world to block some internet content.

Amnesty International's latest report claims that at least 25 countries now apply state-mandated internet filtering, including Azerbaijan, Bahrain, Burma, Ethiopia, India, Iran, Morocco, Saudi Arabia, South Korea, Thailand and Tunisia.

"The virus of internet repression is spreading. The 'Chinese model' of an internet that allows economic growth but not free speech or privacy is growing in popularity," said Amnesty International UK campaigns director Tim Hancock.

"From a handful of countries five years ago, it is dozens of governments today who block sites and arrest bloggers. Unless we act on this issue, the internet could change beyond all recognition in the years to come.

"More and more governments are realising the utility of controlling what people see online, and major internet companies, in an attempt to expand their markets, are colluding in these attempts.

"At the moment we turn on our computer and assume we can see all that there is online. The fear is that we will only be able to access what someone wants us to see."

Internet censorship among governments it is only part of the story, according to Hancock. Bloggers, internet cafés and internet journalists are all being targetted.

"The internet is a bad thing for two groups: governments who are realising that they are losing control of information and are trying to restrict the use of the internet; and the victims of those governments who are imprisoned for simply using the internet to post and share information," said Sami Ben Gharbia, a Tunisian blogger and cyber-activist who now lives in The Netherlands as a political refugee.