Taiwan's central bank said Monday that it wants inbound foreign capital to be remitted out of Taiwan if it is not to be invested in the country, as idle capital has built up over the past few days and driven the local currency higher. Director Lin Sun-yuan of the Central Bank of the Republic of China (Taiwan) 's Foreign Exchange Bureau said that during the four days between Dec. 31 last year and Monday, US$49.03 billion in foreign capital flowed into Taiwan. But only US$17.73 billion of that was invested in the local stock market, leaving the remaining US$31.25 billion idle. The injection of capital forced the Taiwan dollar a combined NT$0.34 higher against the U.S. dollar in trading Friday and Monday, prompting a concerned central bank to issue its warning Monday. Lin said foreign investors are obligated to invest their capital according to its stated purpose. The central bank, he said, has passed the list of foreign institutions that have underinvested their capital to the Financial Supervisory Commission (FSC) for further investigation. An FSC official said that his commission will ask those foreign institutions to explain how they intend to use their money. 'If necessary, the hot money operators will be dealt with case by case.' 