Draghi wrote in the piece for Germany weekly Die Zeit that fulfilling the price stability mandate "sometimes requires us to go beyond standard monetary policy tools", when financial markets "are fragmented or influenced by irrational fears".

"We have to fix such blockages to ensure a single monetary policy and therefore price stability for all euro area citizens. This may at times require exceptional measures," he wrote in the article, released in English by the ECB under the title: "The future of the euro: stability through change".

The ECB is working on the detail of a new bond-buying plan aimed at tackling the euro zone crisis by lowering the crippling borrowing costs facing Spain and Italy. Draghi is expected to detail the plan after the ECB's September 6 policy meeting. (Writing by Paul Carrel)

• A Permanent Economic Emergency