A liberal Chinese journal said that its website was shut down today in what is the latest and most prominent example of a crackdown by Chinese authorities against online freedom of expression.
The website of the Beijing-based Annals of the Yellow Emperor was closed days after it published an appeal for leaders to guarantee constitutional rights including freedom of speech and assembly.
Closure of the website follows censorship by the authorities of similar calls made by a key liberal newspaper.
The crackdown comes despite pledges of change from China's new Communist leadership, headed by president-in-waiting Xi Jinping, which has promised a more open style of governance since the ruling party's congress in November.
Attempts to access the Annals' website today led to a page with a cartoon policeman holding up a badge and the message: "The website you are visiting has been closed because it has not been filed on record."
Editor-in-chief Wu Si said he received a message from the Ministry of Industry and Information Technology, China's Internet regulator, last month stating that the website had been "cancelled".
The information technology ministry did not respond to faxed questions and phone calls made by AFP.
The website closure came a day after censors blocked an article from popular liberal newspaper Southern Weekly which called for the realisation of a "dream of constitutionalism in China" so that citizens' rights could be protected.
David Bandurski, a Chinese media researcher at the University of Hong Kong, told AFP: "The Southern Weekly incident is very important, very unprecedented... this kind of direct intervention by propaganda officials is something we haven't seen."
Asked about the Southern Weekly article, a foreign ministry spokeswoman in Beijing said: "There is no so-called news censorship in China."
Several journalists known for criticism of the government found that their accounts on Sina Weibo were deleted last month, shortly before China - which has the world's biggest population of Internet users - implemented tighter online controls.
The new rules require Internet users to register with their real names, and service providers to remove posts with "illegal information" before forwarding them to authorities.
China came 174th in a list of 179 countries ranked for press freedom in 2011-12 by the advocacy group Reporters Without Borders, falling three places as compared to the previous year.