But Mr Blanchard, who departed the IMF two weeks ago, said radical visions for a full-blown "fiscal union" would not solve fundamental tensions at the heart of the euro.
"[Fiscal union] is not a panacea", Mr Blanchard told The Telegraph. "It should be done, but we should not think once it is done, the euro will work perfectly, and things will be forever fine."
Although pooling common funds, giving Brussels tax and spending powers, and creating a banking union were "essential" reforms, they would still not make the "euro function smoothly even in the best of cases", said the Frenchman.
Any mechanism to transfer funds from strong to weak nations - which has been fiercely resisted by Germany - would only mask the fundamental competitiveness problems that will always plague struggling member states, he said.
"Fiscal transfers will help you go through the tough spot, but at the same time, it will decrease the urge to do the required competitiveness adjustment."