council decis april negoti articl xxiv gatt eec council european commun regard treati establish european econom commun articl thereof regard recommend commiss enlarg commun hellen republ tariff concess renegoti accord articl xxiv gener agreement tariff trade decid sole articl commiss author enter negoti articl xxiv gener agreement tariff trade commiss conduct negoti consult special committe provid articl treati assist task luxembourg april council presid de kone