* Dollar gains as U.S. Treasury yields spike on sell-off
* U.S. tax cut renewal stokes fears about fiscal health
* Euro seen likely to slide back below $1.30 by year-end (Updates prices, adds quotes, details, changes byline)
By Wanfeng Zhou
NEW YORK, Dec 7 (Reuters) - The dollar rose the most against the yen in nearly three months on Tuesday after a proposed extension of U.S. tax cuts triggered higher Treasury yields, though the longer-term impact on the greenback is less clear given an already large U.S. deficit.
The euro surrendered early gains versus the dollar after it did not convincingly break above $1.34. Analysts expect the currency to remain under pressure and slide below $1.30 in coming weeks as fears about the euro zone's debt problems persist.
Benchmark U.S. Treasury yields hit their highest since July as the proposed tax deal sparked concerns over the government's ability to service its debt burden. Moody's Investors Service said it is worried the extension of tax cuts could become permanent, hurting U.S. finances and credit ratings in the long run. For details see [
] and [ ]."We've seen Treasury yields move quite a bit higher and that's boosted the dollar," said Ronald Simpson, director of currency research at Action Economics in Tampa, Florida.
In afternoon trading, the dollar rose 1 percent to 83.45 yen <JPY=EBS>, on track for its biggest daily percentage gain since Sept. 15.
An index of the dollar against a basket of other major currencies <.DXY> gained 0.36 percent to 79.854.
Despite the rise in the dollar, some analysts said deteriorating U.S. fiscal positions could pose risks to the currency in the medium to long term. In recent years, dollar bears have been worried about the ability of the United States to continue funding its large deficits if foreign investors lose faith in U.S. assets.
"There are structural risks to the dollar. The whole world is cutting back on spending and the United States has just announced tax cuts," said Jessica Hoversen, fixed income and currency analyst at MF Global in Chicago.
"However, the economic data has looked better. People are still active buyers of U.S. Treasuries. There are arguments to be made that the dollar won't aggressively resume its downtrend," she added.
FURTHER EURO LOSSES LIKELY
The euro <EUR=EBS> last traded down 0.1 percent at $1.3296 having hit a session high of $1.3401 on trading platform EBS. It had risen after a report suggested Ireland would pass an austere budget on Tuesday. [
] [ ] [ ]Investors continued to sell the euro on any bounce as optimism about an Irish budget was overshadowed by broader worries about the European Union's ability to keep debt problems from spreading.
"If the Irish pass an austerity budget, it alleviates some political uncertainty, but EU finance ministers provided no signals for additional steps to help stabilize European credit markets," said Omer Esiner of Commonwealth Foreign Exchange in Washington.
Hedge fund manager David Einhorn, chairman and founder of the $6.8 billion Greenlight Capital, said he doesn't expect the euro to gain much traction against the dollar as the European situation has yet to stabilize.
"It's still an open question. It's still in progress," he said at the Reuters Investment Outlook Summit on Tuesday.
<^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Take a Look on euro zone debt crisis: [
] Scenarios on euro zone crisis: [ ] Graphics package on Europe's struggle with debt: http://r.reuters.com/hyb65p PDF on yuan offshore market: http://r.reuters.com/byg28q ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^>Mark McCormick, currency strategist at Brown Brothers Harriman in New York, said the euro is also at risk of dropping if China decides to implement a rate cut over the weekend.
The official Chinese Securities Journal reported China's central bank may raise interest rates this weekend to enshrine its shift to a "prudent" monetary policy in the face of rising inflation. [
] (Additional reporting by Julie Haviv and Gertrude Chavez-Dreyfuss; Editing by James Dalgleish)