FOREX-Yen nears 15-year high versus dollar

* Market tests Japan's willingness to intervene

* Dollar/yen on track for fourth monthly gain

* Euro hits record low against Swiss franc (Adds detail, updates prices)

By Wanfeng Zhou

NEW YORK, Aug 31 (Reuters) - The yen on Tuesday neared a 15-year high against the dollar and was headed for its fourth monthly rise as investors shrugged off Japan's latest easing move and bet on yen gains that would again test authorities' readiness to intervene.

Mounting U.S. economic concerns have kept investors away from riskier assets and pushed up the safe-haven yen. Analysts see further gains in the currency, which could eventually prompt Japan to sell yen in the markets to weaken it for the first time in more than six years.

Falling global bond yields also boosted the yen's momentum by encouraging Japanese holders of foreign securities to take profits and return funds into yen.

"The yen is benefiting from very low yields outside Japan," said Daniel Katzive, currency strategist at Credit Suisse in New York. "Japanese investors need some incentive to take risk in foreign markets and that incentive is very much reduced when yields are at these levels."

In midday trading, the dollar was down 0.6 percent at 84.11 yen <JPY=>. It had earlier fallen to 83.96, according to Reuters data, not far from its 15-year low of 83.58 set on electronic trading platform EBS last week.

"The yen has a little further to go," said Katzive. "We think dollar/yen can get down to 82 in the near term."

The euro fell 0.3 percent to 106.83 yen <EURJPY=>.

Japanese Finance Minister Yoshihiko Noda repeated on Tuesday that the government would take decisive action on currencies -- usually seen as code for intervention -- when necessary.

On Monday, the Bank of Japan expanded cheap loans to banks, a move seen as a symbolic gesture that will do little to halt the currency's climb.

"The policy action by the BoJ isn't going to change the market's mood. It would probably take intervention to shake things up a bit," said Vassili Serebriakov, currency strategist at Wells Fargo in New York. "But we're not even sure that would cause a sustained reversal of yen strength."

INTERVENTION RISK

The dollar has fallen 2.7 percent against the yen this month and is down more than 9 percent this year.

Traders say Japanese authorities are expected to buy the dollar against the yen if the dollar slides 3-4 yen in one day. For Q+A on whether Japan will intervene to curb the yen's rise, click on [ID:nTOE67U05E]. <^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PDF on Japan's yen dilemma: http://r.reuters.com/nef47n Insider segment on the yen with RBS Securities Chief Japan Economist Junko Nishioka: http://link.reuters.com/rer38n ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^>

Derek Halpenny, analyst at The Bank of Tokyo-Mitsubishi UFJ, said while "there is a deep reluctance" within the Japanese government to intervene, "the tepid policy steps taken by the Japanese authorities yesterday does shift the risk toward action as yen gains persist."

A raft of U.S. economic releases this week, highlighted by Friday's nonfarm payrolls report, could push the yen higher, analysts said, if they show further deterioration in the economy and weigh on bond yields.

The dollar/yen rate has had a strong correlation in recent months with the yield gap between the United States and Japan, and a fall in Treasury yields also weighed on the dollar.

The yen could also face potential buyback pressure in cross trades such as euro/yen and Aussie/yen, which have attracted some interest because of their larger yield differentials.

Against the dollar, the euro rose 0.3 percent to $1.2705 <EUR=>, helped in part by strong job numbers from Germany. [ID:nLDE67U0IQ]

The euro slumped to a record low against the safe-haven Swiss franc, removing barriers at 1.2900 on the way. The euro fell as low as 1.2878 francs <EURCHF=EBS> on EBS. The dollar fell to a seven-month low against the Swiss francs <CHF=>. (Additional reporting by Steven C. Johnson; Editing by Leslie Adler)