BERLIN (AP) — An influential German business organization is warning that proposals to allow the European Central Bank to buy up bonds of struggling euro countries could seriously damage the single currency.

The ZDH, which represents some 5 million skilled craftsmen, said Friday the "stabilization of the monetary union is no end, in and of itself, to be pursued with no thought to the associated economic, social and societal costs."

It warns that a big bond-purchase program by the ECB could "pose a massive threat to the functioning of the monetary union."

Markets have rallied on hopes the ECB will buy bonds of countries like Spain and Italy, to keep a lid on their borrowing costs.

The ZDH also says national parliaments need to retain control of deciding how taxpayer money is spent.