Former Italian Prime Minister Silvio Berlusconi has unleashed a bitter political debate ahead of a crucial meeting of European leaders in Rome, saying there may be "advantages" in Italy abandoning the euro.

"I do not believe it is a blasphemy to consider leaving the euro, we can think about proceeding with a competitive devaluation," he said.

"While it would certainly not be desirable, it would also have advantages," said the billionaire, one of Italy's wealthiest men who heads a vast media and property empire.