* MSCI world equity index slips as stocks turn south
* Index set for biggest quarterly gain since 1988 launch
* Oil slides but crude set for biggest gain in 19 years
* Declining U.S. consumer confidence overshadows optimism (Updates with U.S. markets activity; changes dateline, previous LONDON)
By Herbert Lash
NEW YORK, June 30 (Reuters) - Global stocks fell on Tuesday after sliding U.S. consumer confidence cast doubts about the strength of a recovery that has put MSCI's world equity index on course for its best quarterly gain since its 1988 inception.
In a sign the worst of the credit crisis and world recession may be passing, crude prices were set to post their strongest quarter in 19 years, despite a 3 percent slide that was sparked by a weaker dollar and the U.S. confidence data.
The Conference Board's index of consumer attitudes fell in June to 49.3 from a downwardly revised 54.8 in May, helping European stock markets to lose gains and halt an early sell-off in the U.S. currency. The data also pushed U.S. stocks lower.
Investors, however, have taken heart in recent data that showed a freeing up of primary bond and credit markets, a cyclical, inventory-driven rebound in manufacturing, an easing of the housing market slump and a tepid rebound in business and consumer confidence.
Authorities have gained traction against the downturn via extraordinary monetary policies, where official interest rates are near zero and long-term borrowing rates have been capped by so-called quantitative easing.
But investors also have questioned whether the "green shoots" that Chairman Ben Bernanke of the Federal Reserve has used to describe an economy on the mend are actually flourishing.
The confidence data underscored an economy still in trouble and cast a shadow over earlier reports that suggested the downward spiral may be moderating. The U.S. equity market sell-off was broad, hitting all 10 of the S&P's sectors.
The consumer confidence data dampened sentiment, said Kevin Kruszenski, head of listed trading at KeyBanc Capital Markets in Cleveland.
"Everybody is trying to connect the dots in terms of positive economic data, or at least data that is just in decelerating decline," Kruszenski said.
MSCI's all-country world index <.MIWD00000PUS> fell 0.87 percent, after paring gains of 0.5 percent.
David Resler, chief economist at Nomura Securities International in New York, said prices may have been getting a bit ahead of events in the last few days.
"This is a wake-up call for the stock market that the economic recoveries typically move in fits and starts, and this kind of (move) in consumer confidence is a revelation that it is not all clear sailing from here," Resler said.
At 1:27 p.m., the Dow Jones industrial average <
> was down 109.28 points, or 1.28 percent, at 8,420.10. The Standard & Poor's 500 Index <.SPX> was down 11.59 points, or 1.25 percent, at 915.64. The Nasdaq Composite Index < > was down 14.80 points, or 0.80 percent, at 1,829.26.Still, the Standard & Poor's 500 Index, a widely followed equity index, was set to close its first positive quarter in almost two years even as the rally has stalled recently.
"We're at that stage now, where bad news will make a bigger dent than decent news," said Howard Wheeldon, a strategist at BGC Partners in London. "And it doesn't take much. Volumes are so low today, they're just tiny."
For the day, European shares fell, with the FTSEurofirst 300 <
> index of top European shares down 1.1 percent to close at 850.17. Over the second quarter the index gained 15.9 percent.The simultaneous end to the month, quarter and half-year point led to increased volatility in foreign exchange trading, exacerbating intra-day moves in currencies.
Gold fell to a one-week low, dropping sharply as the dollar strengthened broadly and crude oil prices tumbled, reducing the metal's appeal as an inflation hedge.
Copper reversed earlier gains to turn negative, weighed down by a firmer dollar and growing perceptions that prices had risen too far and that demand prospects remained poor.
U.S. Treasury debt prices fell slightly as traders booked profits on recent price gains, while euro zone government bonds eased with Bund futures retreating from a six-week high.
The benchmark 10-year U.S. Treasury note <US10YT=RR> was unchanged in price to yield 3.48 percent. The 2-year U.S. Treasury note <US2YT=RR> was down 1/32 in price to yield at 1.11 percent.
The dollar rose against a basket of major currencies, with the U.S. Dollar Index <.DXY> up 0.40 percent at 80.153. Against the yen, the dollar <JPY=> was up 0.20 percent at 96.32.
The euro <EUR=> was down 0.28 percent at $1.4036.
U.S. light sweet crude oil <CLc1> fell $2.18 at $69.31 a barrel.
Spot gold prices <XAU=> fell $9.15 to $927.90 an ounce.
Asian stocks rose on the last day of a torrid quarter, as investors added to trades based on an economic rebound. Japan's Nikkei share average <
> finished 1.8 percent higher. (Reporting by Rodrigo Campos, Edward Krudy, Vivianne Rodrigues and Chris Reese in New York; Brian Gorman, Ian Chua, Joe Brock and Nick Vinocur in London; writing by Herbert Lash) (Editing by Theodore d'Afflisio)