The Association of European Rarities Committees (AERC) provides a good "official" list of birds of the Western Palearctic. The list was originally published in 2003 and was most recently updated in December 2011.
The geographical limits considered by AERC are as defined by the nine-volume Birds of the Western Palearctic - basically Europe, North Africa and a block of the Middle East roughly south and east to Kuwait, but not including Iran nor anywhere east of the Urals and Caspian Sea. For more precise definitions, see BWP.
If you have no strong opinions on list authorities for Western Palearctic listing, it is recommended that this is the one you use.