Germany's two representatives on the European Central Bank's main policy-making body have called for it to prepare to wind down its aggressive stimulus policy as soon as economic conditions allow it.

The comments by Bundesbank president Jens Weidmann and by Sabine Lautenschlaeger, who represents the ECB's supervisory arm on the bank's executive board, highlight Germany's impatience with the direction the ECB has taken under president Mario Draghi.

They also reveal the rift between themselves and supporters of the ECB's current policy of ultra-low interest rates and massive bond buying, which was defended on Monday separately by the central bank's chief economist Peter Praet and by Belgian central bank governor Jan Smets.

"I would like to see a less expansive stance," Jens Weidmann, who sits on the ECB's Governing Council, said at an event in Dusseldorf.

He and Lautenschlaeger said the ECB should start making plans for an eventual end to its stimulus once the recent, oil-fuelled rise in prices becomes sustainable.

"We should prepare for a change in the policy, and as soon as the data is stable and we have a sustainable path towards our objective of price stability, then we are well prepared to do" that, Lautenschlaeger told CNBC.

An outspoken policy conservative, Lautenschlaeger said that if economic data remain supportive, the ECB could discuss and decide on its next step after June.

But Praet, a key ally of Draghi, argued that while the "deflation risk is gone" the eurozone still needs substantial stimulus as the inflation rise could stall or even reverse if the ECB removed stimulus too early.

That came as German business morale hit its highest level in nearly six years in March, suggesting company executives in Europe's largest economy are brushing off concerns about the threat of rising protectionism and Germany's own election issues.

The surprisingly strong business climate index, published on Monday by the Ifo economic institute, added to signs that the German economy is firing on all cylinders at the start of 2017, helped by rising global demand for cars and machinery.

"Wow! Nobody expected such a clear rise," LBBW chief economist Uwe Burkert said. "The concerns about Brexit, Trump and the upcoming elections in France seem to have disappeared."