Italy has paid lower interest rates to raise €12 billion ($15.34 billion) in its first bond auction since the European Central Bank unveiled its bond-purchase plan last week.

Italy's central bank said Wednesday that the interest rates on three-month bonds were 0.7 percent, down from 0.865 percent paid at the last such auction in May. Interest rates on 12-month bonds were 1.692 percent, down from 2.767 percent last month.

Demand for the 3-month notes was 2.25 times the offer, while it was similarly strong for 12-month bonds at 1.65 times the offer.

The ECB plan involves potential purchases of unlimited amounts of a country's short-term government bonds, a step that would lower borrowing costs. Countries must first ask for aid.

Italian Premier Mario Monti has said he doesn't think Italy needs assistance.