A large part of Deadhead culture has always been the exchange of Grateful Dead bootleg recordings, a practice the band encouraged and endorsed -- until now.

The Deadhead bootleg network has advanced in four decades from exchanging cassette tapes through the mail to computer downloads -- but now the band's surviving members have pulled the Internet plug and raised the ire of their usually mellow fans.

Grateful Dead Merchandising -- overseen by Bob Weir, Phil Lesh, Mickey Hart and Bill Kreutzmann -- put the brakes on the Web's Live Music Archive, which offered free downloads of nearly 3,000 Dead concerts, it was widely reported Tuesday.

Deadheads -- widely regarded as rock's most loyal bunch -- have responded with an online petition calling for a boycott of anything related to the group until GDM reverses its position.

GDM recently started selling concert downloads on its own Web site, which could account for the crackdown, RollingStone.com said. It is also possible the Dead's entire live vault could end up on a commercial site, such as iTunes, the music magazine's Web site said.