By Jeremy Gaunt, European Investment Correspondent
LONDON, Sept 27 (Reuters) - World stocks rose strongly for a third straight session of gains on Tuesday with European shares bouncing up 3 percent as investors bet that officials would add to measures to calm the euro zone debt crisis.
Wall Street also looked set for strong gains at the open to follow Monday's rise. Emerging markets gained more than 4 percent.
Yields on long-term core euro zone bonds shot up.
After losing more than 7 percent last week, the MSCI all-country world stock index was up 1.8 percent for a more than 2.5 percent rebound so far this week.
The trigger has been rising expectations following weekend meetings of the International Monetary Fund that European policymakers will act to contain Greece's debt problems and resolve a debt crisis that threatens to do serious damage to the world economy.
Some officials have said that plans are underway to boost the size of a regional bailout fund to cut Greece's debts and recapitalise banks, although others have underlined they are at a very early stage and Germany has said there are no plans to increase the size of the fund.
"Given so much uncertainty at the moment, there is room for both pessimism and optimism. The optimists have taken the forefront on hopes that we could see European politicians getting to grips with the current situation over the coming weeks," said Keith Bowman, analyst at Hargreaves Lansdown.
"But there are still a lot of concerns. Investors remain sceptical."
The pan-European FTSEurofirst 300 index was up 3 percent after rising 1.8 percent on Monday.
Japan's Nikkei gained 2.8 percent.
EURO FLAT
The relative bullishness did not spill over onto foreign exchange markets, where the euro was flat.
"Any indication that European politicians will take fundamental steps to contain the debt crisis is positive for the euro, but we have had so many disappointments and this is not something that can be fixed overnight," said Niels Christensen, currency strategist at Nordea in Copenhagen.
The euro was at $1.3529 , just above an 8-month low.
The dollar was lower against a basket of currencies .
Core euro zone debt prices were lower as the stock markets recovered. They have been rising sharply in a risk aversion trade.
The 10-year Bund yield rose 10 basis points.
But eyes remained on the debt-strapped periphery.
Italy paid 3.071 percent to sell 8 billion euros of six-month Treasury bills, the highest since September 2008 and above Spain's 2.665 percent.
The Spanish sale of three- and six-month bills totalled 3.2 billion euros, above the mid-point of a 2.5 billion euro to 3.5 billion euro target. (Additional reporting by Jessica Mortimer and Atul Prakash; editing by Patrick Graham, Ron Askew)