* Dollar index slides on speculation Fed may suggest more QE
* Aussie rallies after hawkish comments from RBA's Stevens
* Dlr/yen little changed, investors wary of intervention
(Adds comment, updates prices)
By Naomi Tajitsu
LONDON, Sept 20 (Reuters) - The dollar slipped broadly on Monday on speculation the Federal Reserve may flag the need to inject more stimulus into the struggling U.S. economy when it announces its latest policy decision on Tuesday.
The possibility of more Fed quantitative easing -- seen as currency-negative -- highlighted differences in policy among major central banks, as the Aussie hit a two-year high on hawkish Reserve Bank of Australia comments.
The greenback traded in a thin range against the yen due to a market holiday in Japan and as investors were cautious of taking big yen positions after Japan's intervention last week to curb the strength of its currency.
The Fed is expected to refrain from implementing new steps to ease monetary policy on Tuesday, while renewing its promise to keep its portfolio of assets from shrinking.
"The market is expecting that the Fed will keep its options open (regarding the possibility of more QE) and we could we see the dollar depreciate in the very near term as a result," said Lauren Rosborough, currency strategist at Westpac.
By 1142 GMT, the U.S. currency had fallen 0.3 percent against a currency basket, taking the dollar index down to 81.163, near a five-week low of 80.865 hit last week.
The Australian dollar rose more than 1 percent to $0.9470, its strongest since mid-2008, after RBA Governor Glenn Stevens suggested Australian interest rates would rise further.
Gains were capped, however, with traders citing talk of a large option being defended at $0.9475 with expiry at the end of the month. A break above there, however, would prompt traders to target the psychological $0.95 level.
FED AHEAD
A sluggish U.S. recovery has stung the dollar in recent months as it has raised the possibility of more QE, although recent U.S. data -- while still weak -- has shown a slight improvement.
"The consensus is that the Fed won't do anything tomorrow, but if they indicate that more QE may be on the way, it would send a strong signal to sell the dollar during the week," said Kasper Kirkegaard, currency strategist at Danske in Copenhagen.
The euro rose 0.4 percent to $1.3095, helped by the broad falls in the greenback and a rise in European shares, though sentiment towards the single currency was still dented by concerns about Ireland's finances.
Ireland's central bank said the country would need to rethink plans to cut a bloated budget deficit.
Against the yen, the dollar traded down 0.2 percent at 85.66 yen, keeping in a tight range after Japan intervened last week, pulling the U.S. currency up from a 15-year low.
Further dollar gains were capped by its 55-day moving average, which came in at 85.88 yen on Monday, and investors were focused on whether the dollar would break above 86.00 yen.
In addition to the prospect of more intervention, strength in the Japanese currency may subside as speculators have slightly cut long yen positions -- bets it will appreciate.
The latest CFTC data shows net long yen positions fell to 47,642 as of last Tuesday, the day before Japan entered the market, from 52,183 the previous week. Still, speculators further increased bets on more dollar weakness.
The euro slipped 0.3 percent to 9.1952 Swedish crowns as the crown recouped earlier losses after Sweden's election resulted in a hung parliament.