The European Central Bank (ECB) decided to leave the three key interest rates for the euro area unchanged on Thursday after the Governing Council meeting.

It also announced details of the corporate sector purchase programme (CSPP).

Broad financing conditions in the euro area have improved since further actions, including the expansion of the asset purchase program, were adopted by the ECB last month to strengthen monetary stimulus in the euro area, according to ECB president Mario Draghi at the press conference in Frankfurt.

Draghi pointed out that global uncertainties, particularly the downside risks to the global economy and geopolitical risks, persistently weigh on the euro area, although the monetary easing supports consumption as well as investment by improving overall financing conditions.

Despite the moderate increase of the inflation rate from negative territory back to zero in March, "inflation rates could turn negative again in the coming months before picking up in the second half of 2016," said the president of the ECB, on the basis of current futures prices for energy.

In addition, Draghi confirmed the necessity of preserving an appropriate degree of monetary accommodation in order to secure a return of inflation rates towards the target level without undue delay.

As a response to certain criticism from Germany about the effects of negative interest rates, Draghi said, "we have a mandate to pursue price stability for the whole of the eurozone, not only for Germany."

The Governing Council was unanimous in defending the independence of the ECB, he added.

In March, the ECB decided to implement further monetary stimulus measures including cutting the three key interest rates, expanding its monthly purchase of assets by 20 billion euros (22.6 billion U.S. dollars) to 80 billion euros, bringing investment grade euro-denominated bonds issued by non-bank corporations into the asset purchase program, as well as conducting a new serious of targeted longer-term refinancing operations.

According to the details of the CSPP released on Thursday, the purchases starting in June 2016 will be carried out by six national central banks and coordinated by the ECB.