He has cited increasing commitments as a pundit and family reasons as being behind his decision to leave Chris Coleman's backroom team.
"I have enjoyed every moment of my time with Wales. Everyone knows how passionate I am about my country," said Hartson.
"The work I now do as a pundit for the BBC is taking up more and more of my time.
"With another child on the way I need to spend some time with my growing family. I have learnt a lot working with Chris, Kit (Symons) and Osian (Roberts)."
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