* MSCI Asia ex-Japan inches away from 9-month high
* European shares indexes seen down 0.2-0.3 pct
* Euro dips but holds near 6-week high on Greece optimism
* Australian dollar rises after RBA rate cut
* "Fiscal cliff" uncertainty weighs on commodities
By Masayuki Kitano
SINGAPORE, Dec 4 (Reuters) - Asian shares slipped on Tuesday after a plunge in U.S. manufacturing activity hit Wall Street stocks and the dollar, while the euro hovered near a six-week high on optimism over Greece's plan to buy back debt.
Declines in Asian stock markets suggested caution setting in after gains in recent weeks, with investors reluctant to chase shares higher amid continued gridlock in the U.S. Congress over proposals to avert the so-called fiscal cliff - $600 billion worth of tax increases and spending cuts that will be automatically triggered in early 2013.
European shares were expected to open lower, U.S. stock index futures eased and riskier assets such as commodities were also hit, with oil, copper and gold all losing ground.
"Oil markets are starting to come off on the weaker-than-expected manufacturing data and the fact that the U.S. economic outlook remains unclear," said Natalie Rampono, commodity strategist at ANZ in Sydney.
"We are also seeing mixed headlines on the fiscal cliff negotiations, so markets have already taken on a cautious outlook on that account."
MSCI's broadest index of Asia-Pacific shares outside Japan fell 0.2 percent, backing away from a nine-month high reached on Monday.
Australian shares eased 0.6 percent, while Japan's benchmark Nikkei share average fell 0.3 percent.
Financial bookmakers called London's FTSE 100, Frankfurt's DAX and Paris's CAC-40 to open down 0.2-0.3 percent, and S&P 500 futures slipped 0.2 percent.
Global share indexes had risen on Monday after manufacturing surveys showed signs of a recovery, albeit an uneven one, in China's economy and a slower contraction in Europe. But sentiment toward equities soured after data revealed U.S. manufacturing unexpectedly contracted in November to its lowest level in more than three years.
The Institute for Supply Management (ISM) said on Monday that its index of national factory activity fell to 49.5 in November, the weakest since July 2009, as companies worried about whether lawmakers in Washington could reach a budget deal in time to avert a fiscal crisis that may lead to a recession.
Heading into next week, even a hint of progress in the fiscal cliff negotiations could spawn a modest rally, said Vishnu Varathan, regional economist in Singapore for Mizuho Corporate Bank.
"Overall the euro zone noises are coming out positive and I don't see any turning around there. The only real deal-breaker, whatever will send the dollar spiking up and risk really off the table, will be if there is a complete breakdown in the Congress negotiations," he said.
"Right now there is some disappointment here and there, but overall still the consensus is that negotiations will result in some kind of acceptable compromise," Varathan said.
The Australian dollar recovered from initial weakness on Tuesday after a widely expected interest rate cut by the Reserve Bank of Australia (RBA). The rate was trimmed by 25 basis points to 3.0 percent, matching the previous record low.
The RBA said the full impact of rate cuts in the past had yet to be felt, and that recent data confirmed the peak in resource investment was approaching.
The Aussie rose 0.2 percent on the day and last traded at $1.0440, not far from a two-month peak of $1.0491 touched last week.
The euro was flat around $1.3060, hovering near the previous day's high of $1.3076, the single currency's strongest level in about six weeks.
The euro gained as Greek bonds rallied on Monday after Athens announced better-than-expected terms for its planned debt buy-back, boosting chances it will succeed and lead to the release of fresh aid funds.
The U.S. fiscal cliff issue remained in the minds of many investors, underpinning the Treasury market, where benchmark 10-year yields held steady in Asian trading around 1.628 percent.
Brent crude slipped 0.3 percent to around $110.60 a barrel and gold fell nearly 1 percent towards $1,700 an ounce. Copper fell from the first time in four sessions, coming off a six-week high reached on Monday to drop below $8,000 a tonne.
The White House dismissed a proposal from congressional Republicans on Monday that included tax reforms and spending cuts, saying it did not meet President Barack Obama's pledge to raise taxes on the wealthiest Americans.
The Republicans proposed overhauling the U.S. tax code to raise $800 billion in new revenue over 10 years. Obama's opening bid, outlined last Friday, seeks $1.6 trillion in new revenue by allowing the expiry of tax cuts enacted under President George W. Bush for the top two tax brackets.
"Now that the both sides have put out their plans on the table, we can say at least the negotiation is starting. But the way it looks, it will be difficult to get any deal by the second week of December. Probably it's going to take until the third week," said Tomoaki Shishido, fixed income analyst at Nomura Securities.