The single's title was changed from Purple Pills

There has been a long-running feud between Esham and Eminem - who was not part of the tour.

Esham has accused the artist of stealing his material for D12's best-selling album Devils Night.

The Warped Tour was a showcase for many upcoming and established artists including Blink 182 and the Rollins Band.

D12 spokesman Dennis Dennehy confirmed a fight had broken out and that it was being investigated by police.

Warped Tour founder Kevin Lyman confirmed that both D12 and Natas were dropped from the US tour but declined to comment on the incident.

D12's Devils Night album is currently at number four in the UK charts, but its explicit lyrics have caused problems for the band.

Their debut single had to been heavily edited to make it suitable for radio and television.

Purple Pills was changed to Purple Hills to make it more palatable for younger audiences.