The anti-poverty agency said at least $18.5 trillion (14.3 trillion euros) was being hidden in tax havens worldwide in the research paper published Wednesday. It said the figure equalled a loss of more than $156 billion in tax revenue - enough for the world's population to live above the $1.25-a-day "extreme poverty" threshold.

It noted that over two thirds, or $12 trillion, of that global offshore wealth could be found in EU tax havens, including Luxembourg, Andorra and Malta.

"European leaders have absolutely no excuse not to act when you see what proportion of this money is stashed right under their noses," said Natalia Alonso, head of Oxfam's EU office.

"Most governments claim to have no alternative but to cut public spending and development aid, but we've found there's enough potential tax to be had on hidden 'private' money to end extreme world poverty twice over," she added.

The release of the report coincided with a hotly-anticipated EU summit aimed at designing a strategy to combat tax evasion.

Tax dominates talks

European leaders are due to discuss tax avoidance cases by major companies including Google, Amazon and Apple, which have recently hit the headlines.

European officials estimate that widespread tax avoidance costs the EU roughly 1 trillion euros per year. On Tuesday the European Parliament said the four-hour talks must focus on halving that figure by 2020.

France and Britain have largely been the focus of concern over several high-profile tax avoidance schemes. Earlier this week a US investigation revealed that Apple Inc had paid just 2 percent tax on a $74 billion overseas income, mainly by exploiting a loophole in Ireland's tax legislation.

Ahead of the meeting EU summit chairman Herman Van Rompuy said fighting this degree of tax avoidance was "essential."

"In times of tight budgetary constraints and expenditure cuts, combating tax fraud and evasion is more than an issue of tax fairness," Van Rompuy said in his letter of invitation to the bloc's leaders.

The fight for tax transparency "has become essential for the political and social acceptability of fiscal consolidation," he added.

Deal 'not possible'

Fears remain, however, that Austria and Luxembourg may refuse to sign up to measures tightening European tax law. At finance ministerial talks last week both nations refused to approve a scheme which would allow the automatic sharing of bank account information.

Luxembourg Prime Minister Jean-Claude Juncker has warned that a new deal "is not possible Wednesday in Brussels."

ccp/mz (AFP, dpa, Reuters)