The Australian was one of four sports directors in the new professional road team launched by British Cycling performance director Dave Brailsford this year, and was influential in the recruitment and establishment of Team Sky's 26-man squad.

Sunderland confirmed his departure was for personal reasons and to spend more time with his family.

In a statement on his personal website, www.scottsunderland.com, Sunderland said: "My wife Sabine and I have had many long conversations over the last few months and we agree that the well-being of our family and in particular the health of our youngest son Tristan asks for me to increase the time and attention I give to my loved ones.

"Our oldest son Saen has wholeheartedly welcomed this initiative.

"I'm very proud of him for having assumed so willingly a responsible and supportive position during my times away from home.

"Time has come for him to fully enjoy his teenage years.

"The fact that I am taking a step away from my responsibilities as senior sports director for Team Sky does not mean that I will take distance from cycling; this sport has been and will always be an integral part of my life."

Sunderland's son Tristan is suffering from congenital hepatic fibrosis, a life-threatening disease affecting both the kidneys and the liver.

Brailsford acknowledged Sunderland's impact.

He said: "We would like to thank Scott for his contribution to Team Sky.

"He helped us get from the drawing board to being a real road team, working with us from the announcement of the project to our first podium finishes.

"We all wish Scott the very best, personally and for his future career."

Sunderland added: "It has been an incredible journey, helping to set up a new, highly professional team from scratch.

"I'm proud of the team's achievements so far and wish them the best of luck for the rest of the season, their first Tour de France and a successful future."

Team Sky are currently competing at the Giro d'Italia and will begin their first Tour de France on July 3 in Rotterdam.