Google, Yahoo and Microsoft are to back a coalition of academics and human rights organisations to create a code of conduct to protect freedom of expression online.

The code of conduct, which marks a new phase in efforts that these groups began in 2006, will target countries such as China's censorship policies. And will, according to Google, "produce a set of principles guiding company behaviour when faced with laws, regulations and policies that interfere with the achievement of human rights."

Google and Yahoo also hope that the move may help counter the heavy criticism both have received after they were criticised for giving into pressure from the Chinese authorities.

Yahoo was accused of helping to identify a journalist in China who was later arrested and convicted for emailing dissident comments to the US, whilst Google has been accused of providing China with a search engine which is censored in line with Chinese political policy.

It is also hoped that the policy will help ease the pressure put by the US Congress on both these companies and Microsoft. Congress held hearings last year over these corporations involvements with China.

The three companies are working with a number of companies such as the Berkman Centre for Internet and Society at Harvard Law School, Human Rights Watch, Vodafone and the Centre for Democracy and Technology (CDT) to create the policy which will be released later on this year.