Dallas "shock jocks" Kramer and Twitch told listeners to their KEGL-FM evening show that pop singer Spears and her boyfriend Justin Timberlake, of the band 'N Sync, had been involved in a car accident in Los Angeles.
The hoax sparked panic among fans, who called police and fire departments in their hundreds.
The story was then turned into a spoof version of a BBC News Online web page, and the link was sent around the world by e-mail on Wednesday.
The page was removed from the internet after the BBC's lawyers intervened. It had carried the BBC's logo and page design, and said Spears had been hit by a pretzel van in New York.
"There is no truth to the rumour circulating around the world that Britney Spears and Justin Timberlake were involved in a car accident on Tuesday," Spears' publicist Lisa Kasteler said.
Legal threats
Spears, 19, and Timberlake, 20, are both in "great health", she added, and said the stars' representatives are considering legal action.
A BBC spokesman said: "As soon as we were aware of the story the BBC's lawyers looked into it and the service provider pulled it.
"We take the use of BBC branding and copyright material very seriously indeed and always investigate such matters. Legal action will be taken whenever this is necessary."
The site had not been hacked, but a mock-up of a news page was posted on another site by someone familiar with web programming.
False reports
A Los Angeles police spokeswoman said her department spent the night answering calls from reporters and distraught fans of the pop couple.
The Dallas Morning News reported that Kramer and Twitch told listeners that Spears was dead and Timberlake was in a coma.
The DJs said Cedars Sinai Medical Center in Los Angeles had confirmed the report.
Gabrina Soliz, a spokeswoman for the KEGL-FM's corporate parent Clear Channel Communications said they were looking into the incident.
Spears is best known for her singles Oops! I Did It Again and Hit Me Baby One More Time and is due to play at a concert at Los Angeles' Dodger Stadium.
Timberlake is a singer with American boy band 'N Sync, whose album No Strings Attached broke sales records by selling almost 2.5 million copies in its first week of release.