The European Central Bank more than tripled its bond purchases last week to the highest level since late November, spending €3.77bn (£3.11bn) as a calm start to the New Year gave way to an intensification of the euro zone debt crisis.
The ECB's bond purchases face renewed scrutiny after Standard & Poor's mass euro zone rating downgrades on Friday, though the bank has resisted political pressure from within and beyond the euro zone to step up the programme on a major scale.
The latest purchases take the total the ECB has spent on bonds since starting the programme in May 2010 to €217bn.
That is a marked increase on the 1.1bn it bought the week before but remains well below the levels it spent last year as the euro zone debt crisis escalated.
The central bank significantly reduced its bond purchases in the run-up to last month's EU summit as it raised pressure on government leaders to take more aggressive action to arrest the bloc's troubles.
But following S&P's salvo of euro zone downgrades on Friday, and the in the face of a rising risk of an unruly Greek default, traders said the ECB bought Italian government bonds on Monday and that the intervention offset pressure from the downgrade.
Many economists see the ECB as the only institution with firepower to calm bond markets if the debt crisis worsens, but ECB President Mario Draghi and other top policymakers have continued to reject calls for the bank to ramp up its purchases.
Critics, including Juergen Stark who recently quit the bank over the purchases, argue they tread dangerously close to the ultimate ECB taboo of financing Eurozone governments.
City A.M. Reporter