A formal announcement is expected in the next day or two, but the information has been widely "leaked" and published in MSM.
Very sensible advice IMHO, but most unusual in peacetime. I cant read German, and different translations into English differ a little as to whether citizens are REQUIRED to stock up or merely advised to so do.
No neighbouring nations have issued similar instructions, which seems a bit odd, do they expect the disaster or emergency to stop at the border ?
Do we have any German members on here who can comment in detail ? BBC news
Report on BBC, also available from other sources.