"Ai Weiwei considers that you have not only misled him in this regard, but are also potentially deceiving providers of funds to your project as to the extent of Ai Weiwei's involvement in the project, potentially implicating Ai Weiwei in your deception without his knowledge or consent," said the letter, sent on Ai's behalf on April 23.
The letter called on Wishnow to direct Kickstarter to cancel and remove the advertised project, a demand he apparently agreed to. The website currently carries a notice saying the film was the subject of an intellectual property dispute and presently unavailable.
Ai representative Darryl Leung said in an email on Tuesday that the letter was authentic, and that no response had yet been received from Wishnow. "We don't know what the final resolution will be and we don't know whether the film will be shown," Leung wrote.
New York-based Wishnow did not immediately respond to a message seeking comment.
The film dispute marks the latest controversy surrounding Ai, whose international renown has soared in recent years, along with the prices of his artworks. A sculptor, designer and documentary-maker, Ai has irked Beijing by using his art and online profile to draw attention to injustices in China and the need for greater transparency and rule of law.
Despite his fame, Ai has been banned from leaving China since being secretly detained for 81 days three years ago by China's authoritarian communist government for reasons that were never specified. After his release in June 2011, Ai's design firm was slapped with a $2.4 million tax bill, which he fought unsuccessfully in Chinese courts.
In an April 20 email to The Associated Press, Wishnow said the response to the Kickstarter fundraising campaign had been "far more dramatic" than anticipated, and he was working to put the final touches on the movie. He said the film had received more than 2,000 funding supporters.
In an April 9 interview, the cinematographer, Hong Kong-based Christopher Doyle, said the film had been shot over a few days in locations all across Beijing. He said the shoot was conducted in semi-clandestine fashion, describing it as a "very minimalistic simple shooting process."
Footage for the film appears to have been shot without permits or official authorization — and this became part of some of the original hype surrounding the project. However, Ai remains under close government scrutiny and it was unlikely that the authorities did not know about the filming at some level.
Associated Press writer Kelvin Chan contributed to this story from Hong Kong.