NEW YORK —  Madonna has recruited Britney Spears for a virtual appearance on her upcoming tour.

"There is footage being shot of Britney some time this week in conjunction with Madonna's upcoming (Sticky & Sweet) tour," Madonna's publicist, Liz Rosenberg, said in an e-mail Tuesday to The Associated Press. "That is all the information I have available. The rest is a secret."

Rosenberg denied reports that Spears, 26, is shooting a music video.

Madonna guest-starred in a music video for Spears' single "Me Against the Music" in 2003. The singers stirred up controversy that year with an open-mouth kiss at the MTV Video Music Awards.

Madonna, 49, will kick off her tour Aug. 23 in Cardiff, Wales, and wind through European destinations including London and Paris before jumping to the United States in October.

She'll wrap it up Nov. 30 in Mexico City.