The eurozone's debt crisis is far from over despite improving market confidence and "ambitious structural reforms" are needed to boost growth, the Organisation for Economic Cooperation and Development (OECD) said Tuesday.

"The outlook for growth is unusually uncertain and depends critically on the resolution of the sovereign debt crisis," the Paris-based economic think tank said in a report on the economic conditions of the eurozone released in Brussels.

"Market confidence in euro area sovereign debt is fragile," the report added, calling for an ambitious program of reforms in product and labor markets, tax systems and education to rebalance the economies, restore competitiveness, boost growth and bring down stubbornly high levels of unemployment.

While the full gains take time to materialize, many reforms would boost activity even in the short run, said the OECD report.

"Europe is stalling. It needs to get out of first gear and make growth the number one priority," OECD Secretary-General Angel Gurria said at a press conference while presenting the report.

"Weak financial conditions, fiscal consolidation and economic adjustment are restricting demand in the short-term before the long-term benefits on stability and growth are felt," Gurria said, urging "decisive action" to restore confidence and support demand.

The OECD chief also endorsed the efforts made by the heavily-indebted eurozone countries and the European Central Bank (ECB).

"The recent measures already taken to strengthen fiscal discipline, provide liquidity and implement growth-enhancing reforms, particularly in Greece, Italy, Portugal and Spain, are important advances towards a brighter economic outlook, but the challenges remain daunting."

The OECD expected a 0.2-percent economic growth in the single-currency area in 2012, a more optimistic prediction than a "modest recession" forecast by the International Monetary Fund (IMF) and the European Commission earlier this year.