* Yen falls as BOJ meets, governor sceduled to speak 0730 GMT
* Steps such as bond buying expected, to depress yen rates
* RBA raise rates from 3.50 pct to 3.75 pct, as expected
* Aussie faces selling on profits after RBA
By Satomi Noguchi
TOKYO, Dec 1 (Reuters) - The yen tumbled on Tuesday as the Bank of Japan called an emergency meeting to debate easing policy and investors unwound bets that the currency would rise on speculation whether any steps would curb its recent gains.
Euroyen futures jumped and the yen fell after the BOJ shocked markets by saying it would meet at 0500 GMT to discuss economic and financial developments, coming after Japan's finance minister said he was open to a return to quantitative easing.
BOJ Governor Masaaki Shirakawa was scheduled to hold a news conference from 0730 GMT.
The dollar and sterling rose more than 1 percent on the day against the Japanese currency and the euro and Australian dollar also gained nearly 1 percent as investors who had bet they would fall against against the yen were forced to buy them back.
A return to the BOJ's narrow form of quantitative easing, in which it flooded the financial system with cash, has so far seemed unlikely because those inside the BOJ don't think the policy adopted between 2001 and 2006 was very effective.
Analysts and traders said however the central bank could expand its purchases of government bonds (JGBs) as a way of depressing yields to keep borrowing costs down and help avert a recession. Japanese interest rates are already at 0.1 percent.
"The market expects the BOJ to announce it will expand JGB buying but not make a further interest rate cut which is seen meaningless for the economy," said Jun Kato, senior chief analyst at Shinkin Central Bank.
Dollar interbank borrowing costs have fallen below yen ones this year, adding to downward pressure on the dollar, which spiralled to a 14-year low on the yen last week and sparked concern in Japan about the deflationary impact of yen strength.
"If the results of the emergency meeting are disappointing, the yen's rise back could be very sharp," Kato said.
Some analysts said the BOJ could also express its cooperation if the government wanted to intervene to stem the yen's rise.
"Unilateral currency intervention is seen as difficult, but the government could still warn about it," Kato said
The dollar rose more than 1.0 percent against the yen after the BOJ's announcement to 87.49 yen on trading platform EBS, rebounding further from the 14-year low of 84.82 yen.
Traders said the market had been expecting dollar/yen to trade between 85-88 yen as the greenback remains under pressure from the prospect of low interest rates, which has turned it into a funding currency for purchases in higher yielding assets.
Now they said the dollar had potential to rise to 90 yen in the near term.
The euro also rose more than 1 percent to its high for the day so far of 131.28 yen and the Australian dollar was up 1 percent at 79.90 yen.
If the BOJ does come out with concrete and convincing steps, traders said the yen could extend its fall as speculators have been increasingly long yen positions recently.
Yen net long positions saw the biggest jump in over a year in the week ending Nov. 24, according to Reuters data, to 51,710 contracts from 35,552 in the prior week.
In contrast to Japan, the Reserve Bank of Australia raised interest rates as expected on Tuesday, prompting some selling of the Aussie to book profits.
Australia's central bank lifted its key cash rates by 25 basis points to 3.75 percent, saying three hikes in a row was a material adjustment that would help sustain economic growth.
"The Aussie fell quickly after the RBA rate decision because the outcome was in line with what had been expected and prompted investors to take profits," said a senior trader for a Japanese brokerage firm.
The Australian dollar slipped 0.3 percent to $0.9135 after choppy trade down on the RBA's rate hike.
The euro was steady on the day at at $1.5005 and the dollar index, a measure of its strength against six major currencies, was flat at 74.886. (Additional reporting by Kaori Kaneko and Charlotte Cooper; Editing by Joseph Radford) ((Email: charlotte.cooper@thomsonreuters.com; +81 3 6441 1870; Reuters Messaging: charlotte.cooper.reuters.com@reuters.net)) ((If you have a query or comment on this story, send an email to news.feedback.asia@thomsonreuters.com))