SOFIA, Bulgaria — Bulgaria’s government said Tuesday that two of the people behind a deadly bombing attack that targeted an Israeli tour bus six months ago were believed to be members of the military wing of the Lebanese militant group Hezbollah.

The announcement could force the European Union to reconsider whether to designate the group as a terrorist organization and crack down on its extensive fund-raising operations across the continent. That could have wide-reaching repercussions for Europe’s uneasy detente with the group, which is an influential force in Middle East politics, considers Israel an enemy, and has extensive links with Iran.