According to the BBC, officers want to interview the pair over an incident that took place following an N-Dubz gig at Butlins holiday camp in Skegness last Saturday.
Junior Edwards, from Islington, north London, has been arrested on suspicion of rape and common assault.
The incident is alleged to have occurred after Dappy and Fazer, real names Dino Contostavlos and Richard Rawson, went back to accommodation at the holiday camp with Edwards and three women in their early 20s.
Lincolnshire police confirmed that Edwards, 22, was arrested on Sunday at Skegness police station and has since been released on police bail.
"Three further men from the Camden area of London are being sought as potential witnesses in relation to the allegations," a police spokesperson said.
N-Dubz released new album Against All Odds on Monday.