Japan's finance minister raised the prospect of a Group of Seven joint statement on currencies to cool the yen's rally as the dollar tumbled to a 14-year low against the yen on Friday.

In a sign Tokyo was stepping up its warnings of the chance of currency intervention, market sources said the government and the Bank of Japan had been checking dollar/yen rates with commercial banks in the morning.

The greenback slumped to a low of 84.82 yen as investors shunned riskier assets due to concerns about Dubai's debt problems, but it pared its losses after comments by Finance Minister Hirohisa Fujii.

I would respond flexibly to a joint statement on currencies, Fujii told reporters after a cabinet meeting.

Fujii said he was also flexible about contacting currency authorities in the United States and Europe, adding that he was very nervous about currency moves and it was possible Japan could respond.

He declined to comment on intervention, saying he was not in a position to use the word due to commitments with other G7 countries on currency flexibility.

Traders doubted if Fujii's comments were strong enough to reverse the greenback's slump, as joint intervention seemed unlikely. A joint statement might not be enough to rattle investors focused on the likelihood that interest rates in the United States will remain low and on worries about exposure to Dubai's debts, traders say.

The last time the G7 issued a statement on currencies was in October 2008, when rich countries warned that wild swings in the yen threatened financial stability after it surged to a 13-year high against the dollar and a six-year peak versus the euro. The yen rose after the statement as G7 countries stopped short of actual intervention.

I would not be surprised if the G7 or the Group of 20 issues a statement to prevent the dollar from weakening further, although it is unclear if they will act now or wait until a G7 meeting in February, said Koji Fukaya, a senior currency strategist at Deutsche Securities in Tokyo.

But the statement would unlikely be the kind issued in October last year, because the current situation stems from a weak dollar.

The yen has risen 5.3 percent since the end of 2008. In trade-weighted terms, its rise is also modest with the currency well below highs hit in January, as this graphic shows:

http://r.reuters.com/dys63g

I have not heard of intervention at this point but in the future there will be various options and if necessary I'll talk to ministers involved, National Strategy Minister Naoto Kan told reporters.

Japan's authorities intervened heavily earlier in the decade to stop a rising yen from harming exports, but they stopped doing so in March 2004 after selling 35 trillion yen over a 15-month period to shield a struggling economy.

Japan's Democratic Party-led government, which swept to power in an election in August, has criticized the previous administration for catering to the country's exporters by keeping the yen weak.

But this criticism has come back to haunt the new government, in power for just two months, as the dollar's tumble against the yen threatens export earnings and could push the economy back into recession.

The pressure is mounting on Prime Minister Yukio Hatoyama's administration as public support for his cabinet is slipping and the Democrats face an election for the parliament's upper house next year that will determine whether it can govern without needing the support of two small coalition partners.

The dollar has been falling broadly recently as expectations that interest rates in the United States will remain low, speculation that Japan won't intervene in currency markets, and a bout of risk aversion all snowballed into a sell-off.

Banking Minister Shizuka Kamei also weighed in on the dollar's slump against the yen, saying he had talked to Fujii about coordinated international action.

(Additional reporting by Tokyo newsroom; Editing by Hugh Lawson)

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