NEW YORK - June 15, 2010 - The risk of a double-dip Depression is growing, especially in the euro zone, where restructuring Greece's debt is inevitable, famous economist Nouriel Roubini told CNBC Tuesday.

Moody's became the second major agency to cut Greece's debt ratings to "junk" late on Monday, as it admitted that the country does not face immediate liquidity problems due to a joint IMF/EU aid package, but that the austerity program will probably weigh on its economic growth prospects.

"I would say that the risk of a double-dip (Depression) is highest in the euro zone… I would say there is a more than 50% probability, if not of a technical double-dip then of economic stagnation in the area,” said Roubini.

"The downside risk to growth is significant so taking stimulus away now is a huge mistake," he warned.

There will be "massive deleveraging" of the consumer and of the private sector in the euro zone and in the UK, according to Roubini.

"What we have to do is avoid a double-dip (Depression), because authorities will not be able to fight it this time,” he said. "The trouble is if there is a double dip there won't be the policy bullets."

Greece should restructure its debt "in an orderly manner" because even with the EU/IMF help it will not be able to shake off the burden of debt, Roubini said.

"Take Greece, even if they follow the IMF program… their public debt is going to stabilize at 145% debt to gross domestic product. What joke is that?"