Bloggers are rattling journalists with their constant online attacks and criticisms, with some questioning the motivations of certain online diarists.

Journalists say while blog insights can be healthy, fresh and informative, some cyber critics are just "nasty", "toxic" and seeking to undermine high-profile reporters through publishing insults, insinuations and abuse. 

Bloggers have so far scored several media coups over mainstream reporting, including blowing the whistle on the suspect National Guard documents used by CBS's Dan Rather in a report on President Bush.