I suspect that Italy may very well require disclosing foreign assets for all those subject to filing an Italian tax return. Most of the other European countries require something like this, due to the OECD anti-money laundering rules. It's normally just a matter of reporting the financial accounts (and possibly foreign assets, like land and buildings) with information about the account numbers and address of the bank or financial institution holding the funds.
There is a similar reporting requirement here in France (part of the income tax forms) - for foreign bank accounts and foreign "assurance vie" (i.e. "life insurance" contracts with an investment component).