(Recasts, adds details) TAIPEI, March 10 (Reuters) - Taiwan’s central bank announced on Wednesday a large spike in its currency intervention spending last year, possibly putting the trade-dependent island in Washington’s crosshairs to be labelled a manipulator. The central bank said it bought a net $39.1 billion to intervene in the foreign exchange market, as it stepped up efforts in November and December to “avoid serious disorder”. It has been worried about the strong Taiwan dollar, which has gained 0.6% against the greenback so far this year, making the island’s exports more expensive and feeding concern in Taipei that Washington may call it a currency manipulator. The Taiwan dollar’s 5.6% gain against the greenback last year was among the strongest in Asia. In December the U.S. Treasury added Taiwan to a “monitoring list” of countries whose currency practices have caused concern, the first time the island has appeared on the list since 2017. The $39.1 billion figure is well above the roughly $13.5 billion that could cause the U.S. Treasury Department to label it a currency manipulator. Taiwan is a small and open economy and it is “necessary” to keep the Taiwan dollar at a “relatively stable” level, the central bank added. The central bank’s report to parliament comes ahead of its governor Yang Chin-long taking questions from lawmakers on Thursday. Taiwan also meets Washington’s two other criteria by which it could be labelled a manipulator. It has a trade surplus with the United States that is at least $20 billion over a 12-month period and a current account surplus that is at least 2% of gross domestic product (GDP) over a 12-month period. Taiwan’s trade surplus with the United States hit $29.9 billion in 2020, according to official data, almost $7 billion more than in 2019, while the current account surplus last year was around 11% of GDP. Taipei is keen to negotiate a free trade agreement with Washington and a currency manipulator label could affect that. Taiwan’s tech-focused economy has benefited from global demand for laptops, tablets and other equipment to support the work-from-home boom during the COVID-19 pandemic. (Reporting by Liang-sa Loh and Yimou Lee; Writing by Ben Blanchard; Editing by Jacqueline Wong)