* Canadian dollar soars after BOC announcement
* Dollar drops to 15-year low versus yen
* Euro falls to all-time low versus Swiss franc
(Adds details, updates prices, adds byline)
By Wanfeng Zhou
NEW YORK, Sept 8 (Reuters) - The euro rose against the dollar on Wednesday, buoyed by successful bond auctions in Portugal and Poland that made the single currency's fall the prior session look overdone.
Tuesday's concerns about the European financial sector remained, however, helping lift the yen to a 15-year high against the dollar and the Swiss franc to an all-time peak versus the euro earlier in the global session.
While the rally in the yen and franc eased as the New York session got under way, with global share prices gaining, analysts cautioned that investors remained cautious about taking on risk.
"People have gravitated tentatively back towards the equity market. That has helped the euro to climb off its lows," said Dean Popplewell, chief strategist at FX brokerage OANDA in Toronto. "Investors are still relatively uneasy about the financial situations in Europe."
The euro was last up 0.4 percent at $1.2736 EUR=, trading between a peak of $1.2763 and a low of $1.2660 earlier.
The single euro zone currency tumbled 1.5 percent versus the dollar on Tuesday after a news report that recent stress tests of European banks sector underestimated some lenders' holdings of potentially risky government debt.
Support comes in around the 100-day simple moving average around $1.2670, followed by $1.2605, the 50 percent retracement of the euro's May-to-August rally.
"For the euro to keep weakening, we need confirmation of bad news, not just chatter from the local press," said Peter Frank, currency analyst at Societe Generale in London. He said the next risk for the euro was Hungary, which must find a way to plug a gaping hole in its 2010 budget. [ID:nLDE6871J1].
The euro also gained support after Ireland's finance ministry said nationalized lender Anglo Irish Bank would be split to wind down its assets. Concerns about how Ireland dealt with the troubled Anglo Irish Bank [ANGIB.UL] had weighed on investors recently. [ID:nLDE6871VE].
The Canadian dollar soared against its U.S. counterpart after the Bank of Canada raised its key interest rate by 25 basis points to 1 percent and left the door open for further rate hikes. The greenback was last down 1 percent at C$1.0373. [ID:nN08176437]
The dollar fell as low as 83.34 yen on electronic trading platform EBS JPY=EBS and 83.35 on Reuters data, its lowest since 1995, when it struck an all-time low of 79.75. It was last at 83.87 yen JPY=, up 0.1 percent on the day.
Persistent buying by investors seeking a temporary refuge in the yen helped push the greenback through a major option trigger below 83.50 yen, again testing the Japanese authorities' pain threshold for strength in their currency.
Bank of Japan Governor Masaaki Shirakawa reiterated his reluctance to return to quantitative easing although he indicated the central bank was weighing its options. Finance Minister Yoshihiko Noda again warned he would take decisive action if necessary. [ID:nTOE687026]
"The legitimacy of such talk is still in question until we see some actual action," said Sacha Tihanyi, currency strategist at Scotia Capital in Toronto.
The euro rose 0.5 percent to 106.83 yen EURJPY=, after earlier threatening to revisit August's nine-year low just below 105.50.
The euro fell to a record low versus the Swiss franc of 1.2765 francs on EBS EURCHF=EBS and traders saw little chart support until 1.2700. The dollar hit a nine-month low of 1.0060 francs on EBS CHF=EBS.
The U.S. dollar showed little reaction to the Federal Reserve's Beige book report. The U.S. central bank observed "widespread signs" that economic growth had eased in the six weeks through the end of August. See [ID:nWAL8KE6JM] (Additional reporting by Nick Olivari; Editing by Andrew Hay)