There is a website I've seen, put up by some European hunters, that details the laws in every single European country, in alphabetic order. I don't have the link, but perhaps someone else has it that can post it here. Reading it will seem downright daunting, for all but a few countries there :P

But what's wierd is, there is no shortage of hunters, in even the most supposedly protective/strict countries. If you were to talk to the hunters in those countries, and ask them about the laws that "seem" to say "not allowed", they will tell you that those rules apply to federal land, protected historical sites, etc.. There would be nothing to stop you from detecting a farmer's field, with permission. Or, they'll simply tell you that they hunt "in the forests" and don't make waves. The rules web sites may not specify public verses private land, as it's just assumed that the reader is inquiring of the government rules, thus it is government land that the text is applying to. But some have thought it means the entire country or whatever.
The same thing might be said of the USA too, if a foreigner were coming over here, and wanted to know "can I metal detect?". Depending on how he phrased the question, and who he asked, he might find a consulate or bureaucrat to tell him "no detecting in the USA". Reason? It's being couched in terms of ARPA, or Mel Fisher salvor rulings, fed or state parks, etc... Yet we all know that you can detect here till your blue in the face, as long as you don't be a nuisance and tromp on sensitive stuff.