States issue licences in accordance with the recommended practices of annex 1 of the International Civil Aviation Organisation. There is no such thing as an ICAO licence. Almost every country on Earth is a member of the ICAO, in much the same way as they are nearly all members of the United Nations.
The JAA licence conforms to the ICAO recommended practices for licensing, as does the FAA licence, The Australian licence, The Japanese licence,The Brazilian Licence, Canadian Licence, South African Licence , and hundreds more besides. In fact it is almost impossible to find an
issuing authority where the state or collection of states is /are not a member of the ICAO.
It seems to be a term used by people who are reluctant to mention the name of their own state of issue, and with the implied suggestion that being an "ICAO licence" means it has any more validity than virtually any other licence?
This is what the ICAO have to say on the point:
ICAO licence or international licence
ICAO does not issue any licences. Licences issued by ICAO Contracting States on the basis of Standards and Recommended Practices of Annex 1 – Personnel Licensing, are habitually called ICAO licences. This has led many to believe that there is a specific ICAO or international licence. The fact is that there is not one single international licence issued by ICAO or any other organization. States issue their own licences based on national regulations in conformity with Annex 1 specifications and validate licences issued by other Contracting States on the basis of bilateral or multilateral agreements or the fulfilment of nationally legislated requirements.