* Greenback nears four-month high after Germany extends lockdown * Yen also strengthens as Yellen defends need for higher taxes * Aussie weaker amid flare-up in tensions between West and China * Graphic: World FX rates https://tmsnrt.rs/2RBWI5E By Kevin Buckland TOKYO, March 24 (Reuters) – The safe-haven U.S. dollar approached a four-month high on Wednesday as concerns over a third COVID-19 wave in Europe, potential U.S. tax hikes and escalating tensions between the West and China sapped risk appetite. The yen also strengthened and U.S. Treasuries were bid while Wall Street stocks and crude oil tumbled as investors weighed the outlook for global growth. The dollar index rose to a two-week high at 92.412 early in the Asian session, approaching a four-month top of 92.506 hit earlier this month. The gauge “looks determined to test the top end of a new, higher 91-93 range we think will form in coming weeks,” Westpac strategists wrote in a client note. “Extended European lockdowns have sapped confidence in a synchronised global rebound; meanwhile, the U.S. will have an impressive rebound in coming months amid a strong vaccine roll-out, stimulus payments and economic reopenings,” they said. The euro edged toward a four-month trough below $1.18355 – trading as low as $1.18360 – after Germany extended a lockdown and urged its citizens to stay at home over the Easter holiday. Worries over the pace of the pandemic recovery were also heightened after a U.S. health agency said the AstraZeneca Plc vaccine may have included outdated information in its data. The flight to safety received an additional nudge when Treasury Secretary Janet Yellen told lawmakers that future tax hikes will be needed to pay for infrastructure projects and other public investments. Yellen was testifying to the House Financial Services Committee along with Federal Reserve Chair Jerome Powell, who reiterated that an expected near-term spike in inflation will be transitory. That helped tame U.S. Treasury yields, with the benchmark dipping to 1.6048% on Wednesday, continuing its retreat from a more than one-year high of 1.7540% touched last week. Both Yellen and Powell are also scheduled to testify to the Senate Banking Panel on Wednesday. Human rights sanctions on China imposed by the United States, Europe and Britain, which prompted retaliatory sanctions from Beijing, are adding to market concerns. The safe-haven yen was broadly stronger, and Australia’s dollar – considered a liquid proxy for risk – weakened further on Wednesday. The Aussie slipped to as low as $0.75985, a level not seen since early February, and to 82.49 yen for the first time since the start of this month. In cryptocurrencies, bitcoin languished below $54,000, less than two weeks since hitting a record high of $61,781.83. ======================================================== Currency bid prices at 122 GMT Description RIC Last U.S. Close Pct Change YTD Pct High Bid Low Bid Previous Change Session Euro/Dollar $1.1844 $1.1850 -0.05% -3.07% +1.1854 +1.1836 Dollar/Yen 108.5500 108.5750 +0.00% +5.12% +108.6270 +108.5100 Euro/Yen 128.59 128.65 -0.05% +1.32% +128.7500 +128.4500 Dollar/Swiss 0.9344 0.9338 +0.07% +5.62% +0.9347 +0.9337 Sterling/Dollar 1.3734 1.3754 -0.14% +0.53% +1.3755 +1.3725 Dollar/Canadian 1.2582 1.2588 -0.02% -1.17% +1.2597 +1.2581 Aussie/Dollar 0.7609 0.7626 -0.20% -1.07% +0.7633 +0.7599 NZ 0.6992 0.7000 -0.11% -2.64% +0.7007 +0.6986 Dollar/Dollar All spots Tokyo spots Europe spots Volatilities Tokyo Forex market info from BOJ (Reporting by Kevin Buckland; Editing by Tom Hogue)