The European Central Bank's two former chief economists are criticising the institution's announcement to buy unlimited amounts of government bonds.
Otmar Issing and Juergen Stark said in separate interviews published on Sunday the central bank is overstepping its mandate.
In September, the ECB announced plans to buy bonds to help lower borrowing costs for struggling nations once they get assistance from Europe's rescue funds and meet certain conditions.
Mr Issing told the BBC the bond buying program "is something very dangerous because here the ECB is doing the business that is not done by governments".
Mr Stark, who stepped down over policy disagreements last year, told German news magazine Der Spiegel that the ECB has "overstepped its mandate" and has started to finance government debt.