FRANKFURT, Germany (AP) — Germany's top central banker is saying that Europe needs to take its time setting up a new way to oversee banks and keep their failures from saddling governments with more debt.

Jens Weidmann's speech Thursday echoed calls from Chancellor Angela Merkel for a careful approach to Europe's proposed "banking union," in which the European Central Bank would serve as a supervisory body.

Key details — such as finding money to insure deposits and restructure banks — are not worked out.

Weidmann said the idea "must be thoroughly prepared, and that takes time."

He said the goal can't just be to redistribute risks from countries to the eurozone as a whole, but to also tighten regulation.

German officials have indicated that a planned start date of Jan. 1 may have to slip.