The European Central Bank said Monday it bought euro711 million ($971 million) in government bonds last week as concerns over Portugal's debt crisis flared up again.
The figures include purchases made Thursday and Friday the week before, when analysts said the ECB started buying bonds again after a two-week break.
Because of the way the ECB settles its bond purchases, transactions made late in the week are reported with a delay.
Since it started its bond buying program in May, the Frankfurt-based bank has spent about euro77 billion on the bonds of highly indebted countries like Greece, Ireland and Portugal.
Buying bonds supports their prices and helps keep a government's borrowing costs in check.
Monday's figures represent the largest weekly purchase since late December, when fears spiked that Europe's debt crisis, which has already pushed Greece and Ireland into multibillion-euro international bailouts, would soon spread to Portugal — and possibly much larger Spain.
However, they are still far below where they were in early summer, when the ECB often spent several billion euros a week in an attempt to control market panic in the wake of the bailout of Greece.
Concerns over Spain's ability to repay its debts have abated slightly, but the yields, or effective interest rates, on Portuguese bonds hit a euro-era high last week. Most economists believe that an international rescue of the country is only a matter of time.
In top of its high public debt, Portugal's economy has been growing at an aenemic rate while households have been spending more than they earn.