By Monday (November 21) evening, more than 80 people had posted nude photographs of themselves on a website called "Ai Wei Fans' Nudity -- Listen, Chinese Government: Nudity is not Pornography" -- a rare form of protest in a country where public nudity is still taboo.

They uploaded the photos after Beijing police questioned Ai's videographer on Thursday for allegedly spreading pornography online by taking nude photographs of Ai and four women.

Supporters of Ai, whose 81-day secret detention earlier this year sparked an international outcry, say that the questioning over the nude photographs is China's latest effort to intimidate its most famous social critic.

The videographer, Zhao Zhao, said Beijing police interrogated him for about four hours on the motives behind the photographs.

Ai paid a bond of 8.45 million yuan (1.3 million U.S. dollars) last Tuesday, paving the way to file what he fears may be an ultimately futile appeal on a tax evasion charge that his supporters have said is a political vendetta. The money was raised from contributions from his supporters.

Wen Yunchao, who posted two nude photographs of himself on the website, said he believed the investigation against Ai's assistant was the latest form of "persecution" against Ai.

"From what we can see at the moment, there's almost a hundred people taking part in this, posting their own nude photographs online. Some have a high-level of nudity. Our idea is very simple, we just don't want the authorities to use such a meaningless method to put pressure on Ai Weiwei. Every time they try to do something like that it becomes a joke. Like I said before, every time they move a stone, it falls exactly and accurately on their own foot. I hope they will use a more generous and tolerant approach to deal with Ai Weiwei, and others in similar situations," said Hong Kong-based Wen, who also co-founded the website.

Many of the photos posted on the website were accompanied with politically tinged commentaries.

"Grandpa, is this pornography?" wrote a user, who was photographed bare-bottomed and writing on a wall with the words "'89 political turmoil", referring to the June 4, 1989, armed crackdown in Beijing's Tiananmen Square.

Also following the online drive, dissident Wu Gan said it is a breakthrough for Chinese people to post their own nude photos online.

"In China this should be the first of its kind. In other countries, perhaps some environmental organisations would have already gone out on the street to protest in this way, in a free environment. But in China where it's a more traditional and controlled situation in which no one has citizen rights, I think that this kind of expression is very meaningful. It's a kind of breakthrough," he said.

During Ai's confinement, police had also questioned him about the nude photographs that were taken in August last year, Ai told Reuters.

Ai said the nude photographs had no deeper political meaning and were not meant to criticise the government, but he added that the government could perceive the photos as a "rebellious act".