LONDON (Reuters) - Developed economies will pick up steam this year thanks to an array of ultra-loose monetary policies from major central banks and amid new signs of progress in the euro zone's debt crisis, Reuters polls found.
The surveys of over 250 economists, taken in the past few days, saw 2012 growth forecasts for the euro zone, Britain and Japan revised up, but left unchanged for the United States.
Greece, the source of the currency bloc's debt crisis, swapped its privately held bonds at the weekend for new, longer maturity paper with less than half the nominal value, cutting its debt by more than 100 billion euros ($131 billion).
That paved the way for euro zone ministers to give the final political go-ahead to a 130 billion euro package that aims to keep Athens financed until 2014, allaying fears the debt crisis would escalate further.
Central banks have slashed interest rates to record lows and pumped trillions of dollars into the money supply in a bid to stimulate growth, and a recent slew of upbeat data suggest their efforts have paid off.
The Organization for Economic Co-operation and Development (OECD) said this week economic conditions had improved in the euro zone and Britain while progress detected in previous months in the United States and Japan had continued.
A string of better-than-expected U.S. data, including three straight monthly gains of more than 200,000 in non-farm payrolls, has bolstered optimism about underlying strength in the world's biggest economy.
"I think it's evolving into a self-sustaining expansion," said Mark Zandi, chief economist at Moody's Analytics.
"I think we're pretty close to off and running, assuming we don't get unlucky or nailed by some unforeseen event."
While the pace of economic growth is seen slowing in the first quarter compared to the final months of 2011, despite the stronger jobs numbers, it is expected to pick up steadily throughout the year.
Britain's dominant service sector grew in both January and February, as did the manufacturing sector, purchasing managers' surveys showed, and the country's goods trade deficit widened less than expected in January after touching its narrowest in two years at the end of 2011.
The UK economy will avoid a return to recession and grow 0.6 percent this year and a healthy 1.6 percent next, the poll found.
Across the channel, the battered euro zone is seen emerging from recession next quarter, with tepid growth through to the end of next year, forecasts little changed from February's poll showed.
Japan's economy is now expected to grow slightly faster in the next fiscal year than projected a month ago as rebuilding continues on the northeast coast devastated by the earthquake and tsunami of a year ago.
Although there are still risks such as rising energy prices, economists have scaled down the chances of Japan sliding back into recession to 20 percent in the next 12 months.
That is the lowest probability since Reuters started polling on this question in October 2011, and down from 30 percent in a poll last month.
"The current economy shows a recovery as consumer spending is relatively firm and exports probably started to improve," said Kyohei Morita, chief economist at Barclays Capital.
As economists revised up their growth forecasts, and as fears escalated that higher oil prices would stoke inflation, they cut expectations for further monetary easing.
The likelihood fell that the U.S. Federal Reserve will embark on a third round of bond purchases, known as quantitative easing, and buy more than the $2.3 trillion dollars it has already bought.
After a policy meeting on Tuesday, it gave no fresh clues as to the likelihood of any new moves to buy securities.
The Fed has held rates at ultra-low levels since late 2008 and has said it expects rates will stay near zero until at least through late 2014. The Fed reiterated that expectation on Tuesday.
But economists who took part in the Reuters poll said there was still a significant 42.5 percent probability the Fed will need to hike rates before then, albeit revised down from 50 percent in February.
"Unless high oil prices undermine the recovery, then the Fed is stretching credulity to state that rates will not be moved before late 2014," said Rob Carnell, chief international economist at ING Financial Markets.
Brent crude prices settled at an 11-month high on Tuesday, helped by rising German economic sentiment, improving U.S. retail sales and the Federal Reserve's reiteration that it plans to keep interest rates low.
The Bank of England was not seen adding to its own 325 billion pound ($511 billion) QE program but the Bank of Japan is under pressure to get inflation up to 1.0 percent.
The BoJ on Tuesday kept monetary policy on hold, overruling a lone proposal for more stimulus, but instead expanded a loan scheme targeting growth industries by 2 trillion yen to 5.5 trillion yen.
With Japan's inflation still far from the BOJ's goal the central bank will continue to face pressure from government and markets to do more, analysts said.
"Japan will likely continue to stay under deflation, and the government and the market pressure for the BOJ to implement additional easing is expected to continue," said Yuichi Kodama, chief economist at Meiji Yasuda Life Insurance.
(For poll data click on or)
($1 = 0.7628 euros) ($1 = 0.6355 British pounds)
Polling led by Shaloo Shrivastava in Bangalore; Editing by Catherine Evans