* Japan intervenes for first time in 6 yrs
* Fin Min Noda says will continue to take decisive action
* BOJ detected buying dollars intermittently - traders
By Hideyuki Sano
TOKYO, Sept 15 (Reuters) - The dollar jumped two yen from a 15-year low after Japan intervened to sell yen for the first time in six years, in a move traders said would only buy it time in slowing the yen's persistent rise.
The intervention helped send the euro, Australian dollar and sterling 2 percent higher on the day against the Japanese currency, although it was not clear whether Japan had bought anything other than dollars.
Finance Minister Yoshihiko Noda said Japan intervened in the currency market as the impact of the yen's rise on the economy could not be ignored and that Japan would continue to take action, but that it had been acting solo.
The Bank of Japan acts for the Ministry of Finance in intervention, which traders said continued in the Asian session after the initial bout at around 83.00 yen per dollar which came shortly after the dollar hit a 15-year low of 82.87 yen.
The dollar rose 2.4 percent to 85.05 yen, while the euro climbed 2.2 percent to 110.34 yen.
Traders said Japan may want to bring the dollar up to around 85 yen.
"The BOJ is likely trying to bring dollar/yen above 84.50-70 as chart-wise, if the pair stops below that level, it would be pushed back down," said a trader at a Japanese trust bank.
"The immediate impact from the intervention looks very big, but then the yen will likely eventually go back to the strong side as the actual problem exists in the dollar."
The Bank of Japan started buying the dollar from around 10:30 a.m. (0130 GMT). It also said it would provide ample funds to markets while keeping very easy monetary conditions.
The 85 yen could be a target for Tokyo as many Japanese exporters want to sell the dollar above that level before their half-year book-closing at the end of this month.
It was Japan's first currency market intervention since March 2004, when it capped a 15-month campaign to sell the yen. Then it sold a total of 35 trillion yen.
Noda said Japan would take decisive steps if necessary, including intervention, and watch currency market moves closely.
But few in the market expect a campaign of the same magnitude as 2003-2004, although traders say Japan is likely to keep selling the yen, should it threaten to rise, at least until the end of this month.
Many traders' initial take on Wednesday's action was that the Bank of Japan may be more tactical in its intervention rather than defending a line in the sand at 83 yen.
"Now they've done it, they won't be able to stop intervention halfway. I don't think they have that option," said a trader at a Japanese bank.
The yen had gained fresh momentum on Tuesday after Japanese Prime Minister Naoto Kan won a leadership ballot against a rival seen as more willing to intervene against the yen.
The dollar was also hurt early on by talk that the Federal Reserve could be nearing more quantitative easing but it edged higher on the euro, which slipped 0.2 percent to $1.2978.
The Australian dollar shot to its highest in nearly three months at 79.72 yen.
Japanese intervention also helped boost the dollar against the Swiss franc to $1.0025 from nine-month low of 0.9933 hit on Tuesday. (Additional reporting by Masayuki Kitano and Aiko Hayashi, Editing by Charlotte Cooper and Edwina Gibbs)