The European Central Bank's asset purchase programme to boost the euro zone economy - quantitative easing - is starting to bear fruit.

This is according to ECB Governing Council member Ewald Nowotny. 

"Quantitative easing policies have contributed significantly to economic recovery in the United States and there are first signs of success of these policies also in the European Union," he said.

His remarks were included in a speech for a conference on long-term growth prospects. 

He said monetary policy was less effective than factors such as structural policies, institutions, and research and development in improving countries' long-term growth potential, but could still contribute to a "growth-friendly environment".