President of the organisation Jean-Claude Trichet signalled the move following an emergency Governing Council conference call.
The industry figure said he welcomed the country's attempts to reduce their budget deficits and will actively begin implementing a bond-buying programme.
He noted all euro-area governments need to begin putting their own plans into practice, including encouraging the European Financial Stability Facility to buy bonds on the secondary market.
Jacques Cailloux, chief European economist at Royal Bank of Scotland Group, said: "The ECB is once again intervening as the last line of defence. The intervention will put a halt to the bond-market crash that some member states faced."
The ECB is the central bank for Europe's single currency the euro and aims to maintain price stability across the euro area, which consists of 17 European Union countries.
By Asim Shah