Spies, and dealing with them

(Two posts in one day. I'm in the zone)

So I notice that on one world, the Saben Demesne - I assume - have dispatched about a dozen level 13 spies. I've got enough spies of my own to stop them being able to do anything, but it looks like both sides are similar enough in level that we're pretty much cancelling each other out. Is there a way to actually get rid of them? The only one I can think of involves upping the level of the Intelligence Ministry / Security Ministry / Espionage Ministry, but for the reasons mentioned in the last post, that's liable to take the best part of a week before it'll actually happen....