The European Central Bank (ECB) Executive Board member Yves Mersch said in an interview with the Wall Street Journal on Tuesday that the central bank has no constraints in adding further stimulus measures. He pointed out that the decision was not made yet.

"In terms of fantasy, the sky's the limit. But in the end, we have no constraint in the use, the diversity, or the volume of our toolbox as we see fit. I would not create any expectations in one direction or the other," Mersch said.

He noted that downside risks increased since December, adding that the reasons are falling oil prices and the slowdown in the Chinese economy.