Lawyers are not priests, nor doctors. You are misunderstanding what it means. Attorney-client privilege (in theory) only lasts up to the point where the attorney is sure that something is illegal. If that line is crossed, there is a theoretical reporting requirement (that is not specific to lawyers).
A lawyer most certainly does not have the duty to hide the crimes or confessions of his client(s). Not in the EU, not in the US (nor does a priest or doctor, but they can legally choose to do so in most jurisdictions. Anyone who is not a priest or doctor cannot make this choice : you have to report. In practice I've never seen anyone get sued for not reporting anything outside of financials).
Now as for the interpretation of this ... You have the US way (it's not illegal until a court says it is ... there's something to be said for that), and the EU way. The problem in the EU is that a lot of tax collection agencies are less than subtle and have legal rights that mean you simply don't want to even appear to cross them. In Western Europe, a tax agent has the right to shut down any business without specifying a reason, lock any account without specifying a reason, and take anything from any premise without a reason (or lock it down).
Does this violate the relevant constitutions ? Nobody's successfully challenged it as far as I know. (Yet another reason EU criticism of NSA data collection is ridiculously hypocritical).
That doesn't change the basic principle though. If you go to a lawyer saying "I killed this guy, get me out of it", he may go to the police and report you. While the lawyer is unlikely to get sued for not warning the police, when asked a lawyer MUST testify that this has indeed happened (same thing applies to anyone else for that matter).