Team Sky sports director Steven de Jongh has stepped down after three years, following his admission that he took a banned substance earlier in his career.
As a result of the Lance Armstrong doping scandal, Team Sky asked every member of the team to sign up to a written policy saying they had no past or present involvement with drugs.
Armstrong was stripped this month of his seven Tour de France titles from 1999-2005 for doping.
Sky race coach Bobby Julich left the team on Thursday after admitting he took a banned substance during his riding career.
Another sports director Sean Yates left Sky, although the team said his departure was not a result of their zero-tolerance anti-doping stance.
