(Updates to U.S. afternoon)
* U.S. stocks up in volatile trade after mixed showing earlier
* Russian shares, rouble, rebound
* U.S. short-term yields steady after touching 6-month high
* Dollar edges higher against euro
* China stimulus hopes support emerging market shares
By Barani Krishnan
NEW YORK, March 25 (Reuters) - Stocks on Wall Street rose in volatile trade on Tuesday following robust U.S. consumer confidence data, while Russian assets rose after major industrialized nations warned of additional sanctions without committing to a particular action.
U.S. consumer confidence rose more than expected in March, climbing to its highest level since January 2008. The report was the latest in a string of positive reads on the economy that supported views that softness early this year was related to bad weather and not weakening fundamentals.
"Investors became momentarily concerned about valuation, but that pullback was healthy, and we could see modest gains from here just because equities remain the most attractive place to be," said Kristina Hooper, head of portfolio strategies at Allianz Global Investors in New York, which has $475 billion in assets under management.
Biotech shares were particularly volatile, moving up again by afternoon after erasing gains shortly after the open. Some Internet stocks were up after Monday's mauling.
Investor spirits brightened after a meeting of Western leaders ended with little more than fist-shaking at Russia and news emerged that Moscow's and Kiev's foreign ministers had held an impromptu first meeting.
Sanctions have been imposed against Moscow for its seizure of Crimea, but investors say asset freezes have had little effect.
Shares in Moscow rose, with the Micex Index gaining 2 percent, while the rouble gained 1.5 percent against the dollar.
The Dow Jones industrial average was up 102.79 points, or 0.63 percent, at 16,379.48. The Standard & Poor's 500 Index was up 8.31 points, or 0.45 percent, at 1,865.75. The Nasdaq Composite Index was up 7.49 points, or 0.18 percent, at 4,233.88.
The rebound was an indication that while concerns persist about geopolitical tensions in Ukraine and slowing growth in China, investors were not bearish on equities wholesale.
A measure of world equity markets edged up 0.7 percent.
Long-dated U.S. debt prices fell and short-dated Treasury prices rose, interrupting a four-day trend in which shorter-dated debt weakened more quickly than longer-term bonds.
Two-year and five-year notes have been the worst performers since Fed chief Janet Yellen's remarks that the central bank could raise rates six months after its current bond-buying program ends, suggesting a potential hike by spring of 2015.
That has flattened the yield curve, narrowing the difference between short- and long-dated securities, which suggests more concern about higher rates and a bit less confidence in long-term growth.
Philadelphia Fed President Charles Plosser, a notably hawkish member of the Fed who has argued for an end to the Fed's monthly bond buying program, told CNBC on Tuesday that Yellen had not made a mistake on her timing for a rate hike.
"We've moved a lot since Yellen's press conference last Wednesday," said Charles Comiskey, head of Treasuries trading at Bank of Nova Scotia in New York. "The flattener is a crowded trade, you are seeing people taking off some positions for event risk."
Two-year Treasuries, the most sensitive to interest rate changes, were steady at 0.4250 percent after reaching a six-month high of 0.4650 percent on Monday. The Treasury will auction $32 billion in two-year notes in the early afternoon.
The benchmark 10-year U.S. Treasury note was up 1/32, its yield at 2.7299 percent.
The euro dipped after ECB hawk and Bundesbank chief Jens Weidmann said it was not out of the question for the ECB to buy assets to combat super-low inflation.
European stocks were up 1.3 percent and on course for their biggest rise in almost a month. Adding to the upbeat mood was talk China may launch fresh stimulus to keep up the pace of its economic growth.
"There is a perception that China will look to do some more stimulus," said Michael Hewson, an analyst at CMC Markets. "Personally I think those expectations are way overdone but if the market believes it, then that is all that matters."
The dollar moved higher against most major currencies as the euro and yen came under pressure, along with a number of emerging market currencies.
The euro was last at 1.3827 versus an early low of $1.3750. The comments by Bundesbank's Weidmann, together with a below-forecast German Ifo business sentiment survey, also pushed down yields on euro zone government bonds.
U.S. gold futures were little changed at $1,311.70 an ounce. Spot gold was modestly higher, rising $1.67 to $1310.79 an ounce. (Additional reporting by Marc Jones in London; Editing by Larry King, Susan Fenton and Dan Grebler)