Apostrophes

The apostrophe could be either used or omitted in both cases.  These are all OK:

Council of Ministers' Meeting
Council of Ministers Meeting
ministers' meeting
ministers meeting

As the name of the meeting, usually the noun-noun form rather than the possessive+noun form is chosen, as it saves typeset and looks less cluttered.  Of course, in specific context, one may be more appropriate than the other:  The ministers' meeting was raucous with their shouting and name-calling.