Nouriel Roubini, the New York University professor who predicted the global financial crisis, said Portugal will "soon enough" follow Ireland and Greece in being shut out of debt markets.
The Bank of Portugal forecasts gross domestic product will shrink 1.3pc this year.
The difference in yield between Portuguese 10-year bonds and German bunds, Europe's benchmark government securities, reached a euro-era record of 484 basis points on November 11. The spread was 359 basis points yesterday.
Meanwhile, he said China and other emerging markets risked a "hard landing" as they started raising interest rates to fight inflation.
Some "emerging markets are overheating" and as inflation is accelerating, "they are behind the curve in terms of policy tightening", Mr Roubini said in Moscow yesterday.
"In China, Russia and many other emerging market states that are emphasising growth over fighting inflation, if inflation gets out of hand, they have to tighten more in the middle or later part of this year."
Global rate-setters are growing more concerned that inflation is picking up as the world economy gathers strength and food and oil prices rise.
Some developing-nation central banks in Asia and Latin America are slowing the pace of rate increases and seek to fight inflation by other means. They are aiming to fend off a flood of money-seeking higher yields as rates in major economies remain at record lows.
Inflation was "a problem" as food and energy prices made up two-thirds of consumer-price baskets in some emerging markets, he said. (Bloomberg)