By Luca Di Leo and Michael S. Derby

A top European Central Bank official said Wednesday efforts to buy government bonds have helped calm financial markets, and he didn’t rule out buying private securities, too.

“We have seen some results. Markets are slowly improving” because of the purchases, European Central Bank Executive Board member Lorenzo Bini Smaghi said. When it comes to the potential purchase of private paper such as corporate bonds, he said “it would just be in certain markets.”

In May, the European Union created a $720 billion rescue fund for euro-zone members facing problems selling debt in the public markets. As part of that effort, the European Central Bank in a surprise U-turn said it would purchase euro-zone government debt to help support the smooth functioning of debt markets.

But in contrast to the Federal Reserve and the Bank of England, the ECB didn’t provide an overall amount for the purchases, and it also said the liquidity pumped into the market in this way would be withdrawn–or “sterilized”–to prevent fueling inflation. The purchases have been controversial, particularly with German central bank officials. Amounts purchased have been moderate–in the week to June 11, the ECB purchased EUR6.7 billion in government debt.

Bini Smaghi said that not providing an overall amount for the purchases gave the ECB “more flexibility.”