Indonesian central bank foreign exchange reserve decreased to 108.8 billion US dollar at the end of January from that of 112.78 billion U.S. dollar at the end of December, as firms demand on U.S. dollar rises, of dollar official said here on Thursday. "Today (Thursday) we release a big decline on forex reserve, to meet the big demand from corporate while the supply remain limited at the beginning of the year," Hartadi Sarnowo, central bank deputy governor, was quoted by detik online, one of the leading portal in the country, as saying. The deputy said that the bank would keep intervene the market to ease volatility of rupiah. Indonesia has suffered a trade deficit as demand of oil subsidized oil rise that increase import cost of the commodity, but in December, the deficit narrowed to 150 million U.S. dollars from 610 million U.S. dollars in November, the national statistic bureau said on Feb. 1.