Key international bloggers, experts and writers helped to produce the guidelines, such as US journalist Dan Gillmor and Canadian net censorship expert, Nart Villeneuve.

"Bloggers are often the only real journalists in countries where the mainstream media is censored or under pressure," Reporters Without Borders said on its website.

"Only they provide independent news, at the risk of displeasing the government and sometimes courting arrest."

Blog clamp-down

Included in the booklet, called The Handbook for Bloggers and Cyber-dissidents, is advice about how to blog anonymously, as well as how to identify the most suitable way to circumvent censorship.

It also outlines some help on developing ethical and journalistic values.

Blogs - easy-to-set-up diary-like websites - are proving increasingly popular on the net as vehicles through which people can publish their own thoughts.

Technorati, a blog search engine, tracks more than 17 million blogs globally. Blogs can be anything from personal diaries, to technology news, and political comment.

Many have turned to blogging in countries where mainstream media is restricted. But they are increasingly being targeted by strict authorities.

Iranian authorities have been clamping down on mainstream media for some time, but it has recently turned its attention to cyber-dissidents and bloggers.

Campaign groups say at least two dozen Iranian bloggers have been jailed as a result of the clamp-down. It is estimated that there are some 46,000 bloggers in the country.

The issue of blog censorship and freedom of speech is truly global, however.

In June, Microsoft's MSN Spaces site in China started to block blog entries which used words such as "freedom", "democracy" and "demonstration".

Microsoft said the company abided by the laws, regulations and norms of each country in which it operates.

China recently introduced regulations that required all blog owners to register their sites with the state by 30 June.

And on Wednesday, two Chinese Singaporeans appeared in court charged with posting racist remarks about minority Malays on the net.

The blogger booklet can be downloaded from the Reporters Without Borders website in English, French, Chinese, Arabic and Persian.