Defacement attacks are frequent but the scale of what the previously unknown Chinese wing of the group and hackers invited via Twitter launched from March 30 onwards is still unusual.
The full list of attacked domains posted on Pastebin has now reached 501 after rising in recent days, some of which were defaced more than once after Chinese officials regained control.
"Your government controls the Internet in your country and strives to filter what it considers a threat for it," read the opening text of the defacement message posted on many of the sites.
"In the defaces and leaks in this day, we demonstrate our revolt to the Chinese system. It has to stop! We aren't asking you for nothing, just saying to protest, to revolt yourself, to be the free person you always want to be," continued a message on Pastebin backed up with a Chinese-language translation.
Defacements were accompanied by The Who's 1971 song, Baba O'Reilly, which famously contains the protest refrain "teenage wasteland."
The following protest message was also posted to two sites:
"Dear Chinese government, you are not infallible, today websites are hacked, tomorrow it will be your vile regime that will fall. So expect us because we do not forgive, never. What you are doing today to your Great People, tomorrow will be inflicted to you. With no mercy," it read.
Most of the sites appear to have returned to normal, but the attacks are another example of how vulnerable large numbers of such websites can be to a determined and coordinated group of hackers out to create maximum nuisance.
Hackers sympathetic to the Anonymous movement have now defaced so many sites it would probably be easier to state which high-profile companies and governments haven't been hit.
However, hacking is no longer an act that can be carried out with impunity, as the police sweep of LulzSec members last summer demonstrates.
One of these accused, Ryan Cleary, was re-arrested in March for breaching his bail conditions after being arrested for allegedly DDoSing the website of the UK's Serious Organised Crime Office (SOCA).
This story, "Anonymous Hackers Deface 500 Chinese Government Websites" was originally published by Techworld.com.