BRUSSELS (Reuters) - European Union foreign ministers evaluated grounds on Monday for sanctions against Turkey over a Mediterranean gas dispute before the bloc's leaders decide at a summit on Dec. 10-11 whether to make good on their threat to impose punitive measures.

Turkish President Tayyip Erdogan said his country would not "bow down to threats and blackmail" but repeated his call for negotiations over the conflicting claims to continental shelves and rights to potential energy resources.