It will be years before the euro zone's peripheral economies -- Greece, Ireland, Portugal and Spain -- recover strongly from recession or weak growth, high unemployment and raging budget deficits, a Reuters poll showed on Thursday.

The survey of around 30 economists, taken over the past week, painted a bleak outlook for the debt-ridden states have threatened the existence of the common currency bloc.

Growth forecasts for next year and 2013 were slashed as unemployment rates across the four countries show little sign of falling to around the bloc average until 2014 at the earliest.

In many cases, the Reuters consensus is far below official government forecasts for growth.

Ireland and Spain are expected to fare best of the four countries in 2012, with 0.7 percent growth, and nothing at all for Madrid. Greece and Portugal are each expected to shrink by about 3 percent, digging an even deeper hole in their state finances.

The intensifying debt crisis and the likelihood of further austerity measures are going to take a heavy toll on domestic spending and there is little sign that the external sector will be able to take up the slack, said Ben May at Capital Economics.

These economies are likely to fall back.

There are concerns the debt crisis has spiralled out of control and the euro zone is struggling to design a fired-up bailout fund capable of protecting Italy and Spain nearly a month after European leaders agreed on a plan.

Greece, Ireland and Portugal have already received support from the European Union and the International Monetary Fund. Italy and Spain together need to raise 570 billion euros next year in short and long-term financing, according to ABN Amro.

Rating agency Fitch downgraded Portugal's rating to junk status on Thursday, citing large fiscal imbalances, high debts and the risks to its EU-mandated austerity program from a worsening economic outlook.

And a failed German government bond auction on Wednesday deemed a disaster sparked fears that even the safe-haven status of Europe's biggest economy could be under threat.

The euro zone is unlikely to survive in its current form, according to a separate Reuters poll of leading economists and former policymakers published on Wednesday, which said a new core euro zone with fewer members was a possible solution.

Below are detailed findings from the poll, by country:

GREECE

Greece's economy is going through its longest recession since the Second World War. GDP is expected to contract for a fifth consecutive year in 2012, by 3 percent, having shrunk by about 15 percent from its peak. Virtually no growth is expected in 2013 either.

The unemployment rate is hitting record highs and could exceed 18 percent next year and is much higher for youth, at almost 44 percent.

Greece's spectacular economic decline is mainly the result of huge wage and pension cuts in the public sector, job losses in the private sector, and tax hikes imposed as part of two international bailouts.

EU leaders agreed last month to cut the country's debt owed to private bondholders by 50 percent -- an unprecedented move in euro zone history.

A new government of national unity, led by former ECB Vice President Lucas Papademos, was sworn in earlier this month, with a mandate to see through the debt deal and call elections early next year.

But political uncertainty remains high because the conservative New Democracy party, the front-runners to win the poll, have said they would try to renegotiate the austerity policies when in power, even though they say they subscribe to its broad budget targets.

IRELAND

Ireland's prospects have improved since it was forced into a humiliating bailout this time last year and it is expected to grow 1.6 percent this year, followed by just 0.7 percent next and 2.0 percent in 2013.

Dublin is far more optimistic. It sees GDP growth averaging around 2.8 percent per annum from 2013 to 2015 compared to three percent previously.

Ireland needs medium term growth of around 2.5 percent to ensure its debt, set to peak at 118 percent of GDP in 2013, is sustainable.

Ireland's banks, at the root of the country's crisis, have been recapitalised at a cost of 70 billion euros and are being radically downsized. A new fiscally-conservative government with a record parliamentary majority has replaced a previous administration riven with in-fighting.

Dublin is meeting its budget targets without the sort of social unrest that has plagued Greece and crucially Ireland also won a 9 billion euros reduction in the cost of its European rescue loans over the summer.

But there are serious headwinds which could thwart Prime Minister Enda Kenny's ambition of exiting the 85 billion euros rescue package in 2013 and returning to market funding that year.

So far, it has relied on exports, which on a gross basis account for more than 100 percent of GDP, to pull it through but fears of renewed recession in the euro zone could throw it off course.

The domestic economy is still mired in the legacy of a debt-fuelled property crash and it needs to be revived if strong medium-term growth is to be attained. With the government only mid-way through an eight-year cycle of austerity, that looks a tall order.

PORTUGAL

Portugal is headed for its worst recession since the 1970s next year as sweeping austerity measures imposed by the terms of the country's 78-billion-euro (67.2-billion-pound) bailout hits the country hard.

The Reuters poll showed expectations for a 1.6 percent economic contraction this year and 2.9 percent next, in line with government forecasts. The poll sees a further 0.9 percent contraction in 2013.

Confidence is at rock-bottom, with unemployment at 12.4 percent -- its highest since the 1980s -- and credit contracting fast as banks cut lending to boost their capital ratios.

The only sector holding up is exports, but that could be fragile as the euro zone crisis spreads to bigger economies like neighbouring Spain, a key export market.

Austerity measures will sharply cut disposable incomes as taxes rise across the board and civil servants face the effective elimination of two months' pay next year as the government suspends holiday and year-end bonuses.

Some economists say the government may still have to adopt more austerity measures if there is slippage on fiscal targets, something that could undermine the economy further in 2012.

The Reuters poll predicts a budget deficit of 4.7 percent of GDP in 2012 and 3.5 percent in 2013, slightly more pessimistic than government forecasts of 4.5 percent and 3 percent.

SPAIN

People's Party leader Mariano Rajoy will face a tough task when he takes office next month after winning an absolute majority at Sunday's parliamentary election.

Economists expect a feeble 0.7 percent expansion this year, in line with recent revised government forecasts for 0.8 percent. But the Reuters poll calls for no growth at all in Spain for 2012.

That assessment is well below an as yet unchanged government forecast of 2.3 percent, and will mean harsh austerity measures will have to be taken to stand any chance of meeting ambitious deficit targets.

The growth picture is looking slightly better for 2013, with a consensus for 1.2 percent. But the unemployment rate is expected to stay above 20 percent until then.

The poll showed the government deficit hitting 6.5 percent of GDP this year, half a percentage point above the government's target, but missing it by a wider margin in 2012 and 2013.

Spain's government faces a daunting task in rebalancing an economy that has yet to finish a restructuring of its banking system, and in which many citizens are burdened by debt.

(Polling by Sumanta Dey and Ashrith Doddi; Additional reporting by Harry Papachristou in Athens, Carmel Crimmins in Dublin, Axel Bugge in Lisbon, Nigel Davies in Madrid; Editing by Ross Finley)