Italy's government debt is unsustainable and needs an orderly restructuring to avoid a disorderly default, economist Nouriel Roubini wrote on Tuesday.

Nouriel Roubini

Italy, with public debt at 120 percent of gross domestic product, has real interest rates close to five percent and no economic growth. It needs a primary surplus of five percent of GDP – compared with the current near-zero surplus – to stabilize its debt, Roubini said in a blog published on the Financial Times Web site.