* Euro hits 16-month high vs yen, 8-1/2-month peak vs dollar * German Ifo rises for 2nd straight month * BoJ expected to ease policy on Thursday By Gertrude Chavez-Dreyfuss NEW YORK, Dec 19 (Reuters) - The euro surged to a 16-month high against the yen and an 8-1/2- month peak versus the dollar on Wednesday, bolstered by better-than-expected German business confidence data and increasing optimism about debt-burdened Greece. The yen also weakened to its lowest in more than a year-and- a-half against the dollar on expectations the Bank of Japan will ease monetary policy at the end of its two-day policy meeting on Thursday. Many analysts said the euro could extend gains against both the dollar and yen thanks to year-end demand from corporate and long-term investors in thin trading conditions. Currency speculators are also cutting short euro positions built earlier this year as worries about the euro zone have eased. Germany's Ifo survey showed business sentiment rose for a second straight month in December, raising hopes Europe's largest economy will get back on track after stumbling a little bit the last few months. The expectations component of the Ifo survey also advanced. "The euro is doing well across the board and there are fundamental drivers here," said Vassili Serebriakov, currency strategist at BNP Paribas in New York. "We had good data from Germany, plus we're getting the sense there is a smooth resolution of the Greek problem." The euro rose 0.9 percent to 112.41 yen, hitting 112.49, its highest since August 2011. Investors took out a reported options barrier at 112 yen. Against the dollar, the single euro zone currency rose to $1.3308, its strongest level since early April. Many analysts said the next target for the euro is the late March high just below $1.34. On Tuesday, ratings agency Standard & Poor's raised Greece's credit rating after the country completed its bond buyback program. S&P gave Greece a stable outlook given the euro zone countries' commitment to support Greece's membership in the European bloc. That helped the euro trade on a firmer note overnight. Tentative signs of progress in U.S. budget talks also helped to lift sentiment toward assets linked to growth. "Well-established trends look to be the best bet for today's session and for the euro it's onwards and upwards," said Shaun Osborne, chief currency strategist at TD Securities in Toronto. "Provided we don't get a 'fiscal cliff' shock, a persistent grind higher looks to be the most likely scenario, which could see euro/dollar in the upper $1.35 area in the next few weeks." If U.S. policymakers do reach a compromise to avert steep tax increases and spending cuts early next year, strategists said currencies that tend to gain on a better global growth outlook - like the euro and Australian dollar - should benefit. The dollar index fell to a two-month low of 79.008. It was last at 79.115, down 0.3 percent. BROAD YEN WEAKNESS The dollar, however, rose against the yen to a 20-month high of 84.61 yen as it broke through an option barrier at 84.50 yen. It triggered stop-loss buy orders above that level. The dollar last changed hands at 84.56 yen, up 0.4 percent. Traders reported steady buying of short-dated topside strikes in the dollar/yen options, reflecting the likelihood of more weakness in the yen. Expectations of looser policy from the BoJ, which tend to weigh on the yen, have been bolstered by a landslide election victory for Japan's Liberal Democratic Party (LDP) at the weekend. The LDP is committed to aggressive monetary easing. The BoJ concludes its two-day policy meeting on Thursday and is widely expected to announce another round of monetary easing. Fourteen of 19 economists polled by Reuters last week said they expected the BoJ to ease this week, most likely by increasing its 91 trillion yen ($1 trillion) asset-buying and lending programme by up to 10 trillion yen. Some analysts, however, warned that BoJ measures could fall short of expectations, leading some to buy back the yen. "Markets are getting pretty excited about tomorrow's BoJ announcement, rightly or wrongly. Profit-taking either into the BOJ or directly after makes sense both in dollar/yen and the Nikkei," said Geoff Kendrick, FX strategist at Nomura in London, who said the BoJ was more likely to take strong measures in 2013.