Blackswan,
I was not able to find anything on the official ICAO web-site, but that was after just 10 minutes of looking. I did find references elsewhere to "ICAO ANNEX 10 Volume III Chapter 9" which gives the list you want.
Searching for that term I came across
http://www.peter2000.co.uk/aviation/...Volume_III.pdf which does contain a list (not necessarily in the format you want, but ...), and I have no idea how up-to-date it is. That said, I'm not aware of any/many changes (to the allocations of ranges of codes to countries) that have happened in the past 5 years. That information is also available from
KLOTH.NET - ICAO 24 bit aircraft ID .