Chinese netizens have begun stripping down to their birthday suits and posting their nude pictures on the internet after dissident-artist Ai Weiwei announced Friday that Beijing police were now investigating his assistant Zhao Zhao for “spreading pornography online”. At the centre of the investigations appears to be a picture entitled “One Tiger, Eight Breasts” which Zhao took last year of Ai Weiwei and four women, all of them nude.

Many of those pictures are now posted on a new campaign site, entitled “Listen Chinese Government, Nudity is not Pornography”. The website bears a striking resemblance to an earlier campaign which encouraged netizens to send in pictures with their sunglasses in support of Chen Guangcheng, the blind dissident who remains under house arrest in Linyi.

Activists who have posted their nude pictures to support Ai Weiwei include some usual suspects — Zuola, who posed as Michaelangelo’s David; Tufuwugan who posted an image of him looking to the mountains with his bare posterior facing the camera; and Hong Kong-based Wen Yunchao, who posed with an effigy of the caonima (“grass mud horse”) covering his family jewels. In 2009, Wen infamously posted a picture of his pubes shaved down to the “t” of the Twitter logo when he embarked on a “de-Maoification” campaign, urging his followers to “get rid of mao”.

In an interview with Gillian Wong of the AP, Zhao said police have already made up their minds that the picture he took of Ai Weiwei and the four women was “obscene”:

They said, ‘This photograph is an obscene photograph.’ I said, ‘I didn’t know that, what’s obscene about it?’ They said, ‘It’s just obscene.’ They’ve already decided that,” Zhao said. No charges have been pressed yet, he added.

Zhao said the investigation at this point appeared to be limited to himself, but that he believed it was part of the authorities’ ongoing campaign against Ai.

“To them so far their efforts have had no effect, such as the tax case, so they are trying this from other angles,” he said. “They are again raising this issue, and will keep repeating this over again. They won’t easily let him off.”