Parts of British Prime Minister David Cameron's EU renegotiation objectives are "highly problematic", the European Commission said Wednesday after Cameron sent his demands to Brussels.

"We see a number of elements that seem to be feasible like finding ways to increase the role of national parliaments, some issues which are difficult like the relation between euro ins and outs, and some things which are highly problematic as they touch upon fundamental freedoms of our internal market," spokesman Margaritis Schinas said.