UPDATE 2-EU official says US uncertainty delaying WTO deal

* WTO negotiators don't know what US wants, EU aide says

* EU sees Doha deal boosting world growth $200 bln per year (Adds byline, more detail from speech)

By Doug Palmer

WASHINGTON, Jan 20 (Reuters) - Uncertainty over the U.S. position in world trade talks makes it difficult for countries to reach a deal by the current goal of December 2010, a top European Union trade official said on Wednesday.

Negotiators in Geneva are unsure whether the United States only needs an adjustment in proposed texts or a major overhaul that takes negotiations back to square one, said David O'Sullivan, European Commission director general for trade.

"Just as importantly, we can't judge whether the U.S. could settle tomorrow on the right terms or whether the daunting political calendar of the Obama administration ... inevitably means that this may be a question for 2011 instead of 2010," O'Sullivan said.

"These uncertainties mean that negotiating partners are somewhat hesitant to engage because nobody wants to propose a top-up of the package, only to be told, 'Thank you very much. We still need more time and we'll come back to this next year,'" O'Sullivan told an audience of trade lawyers and industry officials.

The Doha round of world trade talks was launched in late 2001 with the goal of helping poor countries prosper through trade. Negotiators failed to meet an initial 2005 deadline for concluding the round and have missed others since then.

The EU estimates an agreement could boost world economic growth by $200 billion per year, based on the current outline of the deal. It argues that would give the global economy a much-needed lift at a time when governments have little money left for new stimulus programs.

The pact also would increase economic activity in Sub-Saharan Africa by $17 billion per year, about half what the region receives annually in foreign aid, O'Sullivan said.

The U.S. Trade Representative's office did not respond to a request for comment on O'Sullivan's remarks.

Last year, U.S. President Barack Obama and other world leaders set a goal of finishing by the end of 2010. But after a recent ministerial meeting in Geneva, countries appeared no closer to finishing.

The United States says it needs major developing countries like China, India and Brazil to make bigger major openings in exchange for the farm subsidy and agricultural and manufacturing tariff cuts it is being asked to make.

"We fully understand that there is a significant lack of support in Washington for the current deal ... And I honestly believe everyone in Geneva is willing to look at what it might take to make the (Doha deal) more politically acceptable to the United States," O'Sullivan said.

"But frankly, it would be an illusion to believe that this late in the day we trade negotiators have a better, much more attractive deal in the drawer waiting to be taken out on demand. It doesn't work that way," O'Sullivan said.

While there is still room for improvement, the current package already reflects generous concessions for the United States in agriculture and other areas, he said.

(Reporting by Doug Palmer, Editing by Bill Trott and Alan Elsner)