* Fall in U.S. yields helps support yen
* Traders wary of intervention, some eye 84 yen as target
* Euro hurt by Irish banking woes, economic problems
By Hideyuki Sano
TOKYO, Sept 24 (Reuters) - The yen on Friday stayed near its highest level against the dollar since Japan intervened in markets last week, as the spectre of more monetary easing from the Fed and falling U.S. yields put renewed pressure on the greenback.
The euro also slipped as fresh worries about Ireland's economy and banks raised more doubts about the euro zone's recovery prospects.
Traders remained on guard against yen selling intervention by Japanese authorities, which have been absent since their large intervention on Wednesday last week.
"There hasn't been any intervention even after the dollar fell below 85 yen, which some in the market had thought could be the line in the sand. That may lead to speculation that Japan's real defence line is around 82-83 yen," said Keiji Matsumoto, strategist at Nikko Cordial Securities.
"Nonetheless, many market players will remain wary of intervention for now after their huge intervention," Matsumoto added.
The dollar traded at 84.50 yen, up 0.1 percent from late U.S. levels, but not far from a post-intervention low of 84.26 hit on Thursday.
Japan intervened on Sept. 15 minutes after the dollar hit a 15-year low of 82.87 yen, selling an estimated 2 trillion yen, which would be Japan's largest single-day yen selling intervention.
"Given wariness about intervention, the dollar may be supported above 84 yen for now," said Daisuke Karakama, market economist at Mizuho Corporate Bank.
On the upside, its 55-day moving average, at around 85.63 on Friday, has been strong resistance.
Also pressuring the greenback will be shrinking yield gaps between the dollar and the yen.
The two-year bond yield spread fell to around 29 basis points, the lowest in nearly two years, as expectations that the U.S. Federal Reserve will adopt quantitative easing brought U.S. bond yields closer to Japanese yields.
The euro slipped 0.1 percent to $1.3298, falling further from a five-month high of $1.3441 struck on Wednesday as the common currency suffered from mounting worries over Ireland. Data showing Ireland's economy shrank 1.2 percent in the second quarter slowed the euro's upward momentum as it highlighted the struggles the country faces as it tries to shore up a troubled banking sector.
Uncertainty over the cost of propping up the country's banks triggered concerns Ireland is on the edge of a debt crisis that could drag down other euro zone economies.
The euro traded at 112.40 yen, little changed on the day and off a six-week high of 113.53 yen hit on Wednesday. (Reporting by Hideyuki Sano; Editing by Joseph Radford)