Avramovic, who was first appointed head coach in 2003, and the FAS have mutually agreed that he will not be seeking a further renewal of his contract.
Expressing his appreciation of Avramovic's contributions, FAS President Zainudin Nordin said: "Since joining us in 2003, Raddy has served us well and faithfully. Apart from the victorious AFF Cup campaigns in 2004, 2007 and 2012, Raddy has also done well to spot many young talented players and provide ample opportunities for them to cement their place in the National Team.
"Raddy has played an integral role in the development of football over the past decade and I would like to express our heartfelt appreciation to Raddy for his selfless dedication and hard work. We are pleased that he has met both the targets FAS set for him in 2011/12: To qualify for the third round of the FIFA 2014 World Cup Asian Qualifiers and to reach the final of the 2012 AFF Suzuki Cup."
Avramovic, 63, said: "I am thankful to have the full support of President Zainudin Nordin, General Secretary Winston Lee, FAS management and colleagues, both past and present, throughout my tenure as national coach. They have always done their best to fulfil the national team's requirements and requests, whenever possible.
"I am also heartened to note that Singapore football has progressed well over the years, especially in terms of youth development. I would also like to thank the stakeholders including the S.League clubs, media and the fans for their well-wishes and support over the past nine years, and I wish the Lions all the very best. It is important that all stakeholders continue to work together as a team for the good of Singapore football, especially since we have in place the Strategic Plan and a comprehensive setup which will raise the various aspects of local football, including the national team, to the next level."
On the talent hunt for the next national team coach, Zainudin said: "Through our network of contacts and Sports Recruitment International's deep connections into coaching talent, several candidates for the position of National Coach had expressed their interest over the past few months. However, since Coach Raddy's contract only ends at the end of this year, and in view of the National Team's involvement in the 2012 AFF Suzuki Cup, we did not want to undertake any in-depth discussions until after this major tournament."
He added: "The FAS and Raddy met recently and have mutually agreed that he will not be seeking a renewal of his contract. We have therefore formalised our arrangement with Sports Recruitment International, an international executive search firm with regional offices in Singapore, Australia, Switzerland and the UK, to supplement our own efforts to find the best candidate available to take on the role of Head Coach."
Mr Zainudin noted: "Sports Recruitment International has an in-depth understanding of the global football industry, the Singapore sporting landscape and our requirements. We will work closely with them to identify qualified candidates for consideration. In addition to a proactive search, we will advertise the position so as to cast our net as wide as possible and we welcome applications from suitably qualified candidates.
"We will commence the first phase of the interviewing stage soon. While we hope to finalise the appointment soon, we will not rush into making any decision. In the event that the new national coach could not be appointed in time for the team's first Asian Cup 2015 qualifying match, we will appoint a caretaker coach to lead the Lions on an interim basis."
The FAS will make a further announcement in due course.