Fan sites dedicated to Prince say they have been served legal notice to remove all images of the singer, his lyrics and "anything linked to Prince's likeness", and have vowed to fight what they said was censorship.

The move was a shock to his army of followers and came two months after Prince threatened to sue YouTube and other major Internet sites for unauthorized use of his music.

But by targeting fan sites directly, Prince risks a backlash, and the sites have vowed to unite under the banner "Prince Fans United" and take the matter to court if necessary.

"We strongly believe that such actions are in violation of ... freedom of speech and should not be allowed," said a statement from the three sites -- www.housequake.com, www.princefams.com and www.prince.org.

A company helping Prince control his image and music on the Internet said the fan sites had spun the story so that it was "incorrect and misleading".

"At no time is Prince suing his fans and this is not about freedom of speech," said John Giacobbi, managing director of Internet policing specialist Web Sheriff.

"The current issue is one between Prince's record label and three unofficial Web sites and relates to the use of Prince trademarks and photographs, many of which are Prince's copyright," he told Reuters.

Giacobbi said Prince was expected to issue a full response to the fan sites' statement later on Wednesday.

The sites now feature an image of a hand print with "pfu" (Prince Fans United) written on it.

Prince's agent in London said all matters concerning the artist should be referred to its office in Beverly Hills, where no one was immediately available for comment.

The fan sites said Prince, 49, had demanded the removal of fans' photographs of Prince-inspired tattoos and vehicles displaying Prince-inspired license plates.

They urged Prince to reconsider his decision, but vowed to defend their position in court if need be.

"The law clearly provides for displaying of images of a celebrity's likeness for newsworthy events or matters which are considered to be public interest," they said.

Prince, behind such groundbreaking albums as "Purple Rain" and "Sign O' The Times", is renowned for his unconventional approach to music and marketing.

He performed with the word "SLAVE" scrawled across his cheek in protest against his then record label and changed his name to an unpronounceable symbol.

He gave his "Planet Earth" album away free with a British Sunday newspaper earlier this year, infuriating music retailers but winning plaudits from fans for innovation.