After being appointed in July 2010, King oversaw 40 competitive games and improved the team's UEFA ranking, while they achieved two third-place finishes in their qualifying campaigns.

King also helped to launch the senior international careers of in excess of 25 different players, including the likes of Shane Duffy, Robbie Brady and Jeff Hendrick - who have amassed over 100 caps, collectively, since making their debuts.

Confirming his departure from the Under-21s, King said: "I would like to thank FAI CEO John Delaney and the FAI Board for placing their trust in me at the beginning and for their support over the eight years. I thoroughly enjoyed my time in the role and was honoured to hold such a distinguished position.

"I enjoyed some fantastic experiences and I am proud to have helped move the team on during my period with the Under-21s. I am hugely thankful to all of the players and backroom staff - ranging from coaches, doctors, physios, kit technicians, operation executives, analysts, to media officers - who I was fortunate to work with.

"I take with me some great memories from over the years and moving forward I am excited to continue working with the FAI in the capacity of identifying players to represent Ireland."

FAI High Performance Director Ruud Dokter said: "Under-21 football is one of the most challenging tiers in international football and Noel has done a very good job to keep Ireland competitive in that environment, continually improving players and the team's overall ranking.

"Noel has also helped to develop a lot of players, which continues the good work being done along the elite player pathway. I thank Noel for his work with the Under-21s and look forward to continually supporting him in the Player Identification role."

FAI CEO John Delaney said: "I would like to thank Noel for the time and effort that he put into the Under-21s, where he has brought through a number of players for our senior Ireland team.

"Through the years Noel has held several roles, including a spell as interim manager of the senior team, and I'm sure that he will be successful continuing his work with the Player Identification programme, which runs within our High Performance unit."

The process to recruit a new Head Coach for the Under-21s will begin in due course.