"There's a lot of attention on the AQR, and there's some positioning ahead of the end of the calendar year," said John Hardy, FX strategist at Danske Bank in Copenhagen.
The euro gained 1.1% to $1.3846, and touched the day's high of $1.3894, having earlier touched its highest since October 2011. It has risen more than 10 cents from a low hit in July below $1.28, as the euro zone economy came out of a recession triggered by its debt crisis. Moves were exaggerated because liquidity was thin, traders said, but analysts said the euro was likely to hold its strength into 2014.
"Market price actions tend to be corrected as liquidity comes back, but I doubt that (this will happen) this time around," Hidetoshi Honda, currency strategist at Mizuho Corporate Bank said.
"Although there's no fundamental reasons to draw the euro higher, there's unlikely to be considerable retracement as liquidity comes back because the damage is already done."
Unlike the US and Japanese central banks, the European Central Bank has not been expanding its balance sheet actively, giving an additional boost to the euro. The yen touched a five-year trough against the dollar and euro, dented by a renewed appetite for risk which lifted US and German equities to record highs and weighed on the low-yielding currency.
It is on course to post its ninth consecutive week of falls against the dollar, the longest such period since 1974, when the country was suffering from the aftermath of the oil crisis that started the previous year.
Many economists expect inflation in Japan to peak soon, forcing the Bank of Japan to take additional easing steps early next year to counter the impact of a sales tax hike in April.