IMF's Lagarde urges ECB to consider QE

The European Central Bank (ECB) should contemplate quantitative easing if inflation in the single currency bloc remains low for a protracted period, says International Monetary Fund (IMF) Managing Director Christine Lagarde.

"If inflation was to remain stubbornly low, then we would certainly hope that the ECB would take quantitative easing measures by way of purchasing of sovereign bonds," Lagarde told CNBC on Thursday.

She defines "stubbornly low inflation" as prices remaining well below target in spite of measures being taken to boost inflation.

Read More'Damaging deflation' threatens euro zone: EY

Euro zone consumer prices rose by just 0.5 percent year-on-year in May, down from 0.7 percent in April and well short of the ECB's target of close to 2 percent.

Unlike other major central banks, the ECB has so far resisted embarking on a quantitative easing program, but has said it stands ready do so if needed.

Earlier this month, the central bank unveiled fresh measures to stimulate the economy including taking an unprecedented step on of imposing a negative interest rate on banks for their deposits—in effect charging lenders to park money with it.

Read MoreDraghi announces host of stimulus measures

When asked whether further ECB action may lead to complacency among governments in terms of carrying out structural reforms, Lagarde said: "They all seem convinced that they have to pursue structural reforms, support demand by good solid monetary policy, and continue the fiscal consolidation path they have agreed."