* MSCI Asia ex-Japan down 0.2 pct, Nikkei hits 4-week low
* Aussie hits 6-week low vs USD as Fortescue cuts capex
* Reserve Bank of Australia holds rates steady
* European shares seen flat to lower
By Chikako Mogi
TOKYO, Sept 4 (Reuters) - Asian shares eased on Tuesday on concerns over weakening regional and global economic activity, but expectations of more stimulus from central banks and hopes for progress in tackling Europe's debt crisis lent support.
European equities were seen flat to lower, with financial spreadbetters calling London's FTSE 100, Paris's CAC-40 and Frankfurt's DAX to open down as much as 0.2 percent.
U.S. stock futures were up 0.1 percent, pointing to a somewhat firmer opening on Wall Street, which was closed on Monday for the Labor Day holiday.
MSCI's broadest index of Asia-Pacific shares outside Japan eased 0.2 percent and neared a four-week low touched on Monday, pulled down by a 0.6 percent decline in Australian shares.
Hong Kong and Chinese shares fell as a slew of brokerages started paring back expectations for returns.
Sluggish demand from China, the world's second-largest economy and leading consumer of raw materials, has weighed on Australian equities, with declining commodities prices, in particular the recent plunge in iron ore prices to their lowest since late 2009 , hitting mining shares.
Australia's third-ranked iron ore miner, Fortescue Metals Group, on Tuesday slashed capital spending and cut its expansion schedule for iron ore production.
"The recent sharp decline in commodity prices has caused profits to deteriorate significantly, such that miners are now spending more in capex than they are earning. This is not a sustainable situation," said Credit Suisse analyst Atul Lele.
The Reserve Bank of Australia kept rates steady at 3.5 percent as expected on Tuesday, though it did concede the outlook for China was becoming more uncertain.
The Australian dollar recovered to $1.0264 from around $1.0231 before the RBA decision. Earlier in the day, concerns about slowdowns at home and in China, its largest export market, pushed the growth-sensitive currency to a six-week low of $1.0224 against the U.S. dollar and kept it near a nine-week low against the euro.
Investors were awaiting U.S. Institute for Supply Management manufacturing data later in the day, after similar business surveys on Monday underscored a spreading contraction in manufacturing around the world in August as the euro zone's troubles took a deeper toll on their economies.
The ISM, along with Friday's nonfarm payrolls, is key to gauging the probability of further easing by the Federal Reserve at its Sept. 12-13 policy meeting.
"The ECB meeting this week is important, but the U.S. ISM index will also be key, because if these numbers are bad there is a chance things will turn worse," said Chung Seung-jae, an analyst at Mirae Asset Securities in Seoul.
Japan's Nikkei stock average fell 0.2 percent, after touching a fresh four-week low.
ECB PRICED IN
The euro rose 0.2 percent to $1.2619, within reach of an eight-week peak of $1.2638 set on Friday.
European Central Bank President Mario Draghi told European lawmakers on Monday that the ECB's purchases of short-term sovereign bonds would not breach the European Union's taboo of directly financing euro zone economies.
Markets were already pricing in the ECB on Thursday to at least outline its bond-buying scheme aimed at containing the borrowing cost in struggling economies such as Spain. Such prospects have helped cap Spanish 10-year yields below a critical level of 7 percent.
A prolonged contraction in the euro zone manufacturing index raised expectations the ECB may cut its main interest rates, too.
"While the white swan from the ECB's announcement of a new bond buying programme was welcome, we remain concerned that new white swans will be slower in coming," Societe Generale said in a research note.
"This is nonetheless what defines the main upside. In China and the U.S., the upside is defined by more policy stimulus. Our fear is that such initially white swans, medium-term would turn to black," it said.
Separately, German Finance Minister Wolfgang Schaeuble said on Monday he was sure the country's Constitutional Court at its Sept. 12 ruling would not block treaties establishing a permanent bailout fund, the European Stability Mechanism (ESM), and strong budgetary regulations in Europe.
The ESM, meant to succeed the existing temporary European Financial Stability Facility, will provide a crucial firewall to contain the euro zone debt crisis and the ECB's bond-buying plan is conditional on its deployment.
Precious metals rose on speculation for additional monetary policy, lifting spot gold to its highest since mid-March of $1,696.91 an ounce. The most active U.S. silver futures contract rose nearly 3 percent to $32.38 per ounce, the highest since mid-April, while spot silver stayed near a 4-1/2 month high of $32.31 hit on Monday.
U.S. crude rose 0.8 percent to $97.25 a barrel while Brent inched up 0.3 percent to $116.07.
Asian credit markets firmed, tightening the spread on the iTraxx Asia ex-Japan investment-grade index by four basis points.