(Adds Tombini comments on size of swap program, context)
By Luciana Otoni and Alonso Soto
BRASILIA, Dec 16 (Reuters) - Brazil's central bank will keep intervening in the foreign exchange market next year but could reduce the scale of these operations, which are aimed at countering the slide in the country's currency, the real, which has stoked inflation.
Central bank chief Alexandre Tombini on Tuesday told reporters the bank will decide in coming days whether it will reduce the daily supply of currency swaps to as little as $50 million at the start of 2015 or keep it unchanged at $200 million.
Some investors had doubts on whether the bank would continue selling these swaps next year after Tombini had previously said the program has met its goals.
Still, his comments were not enough to fully ease investors' fears of additional currency losses. The real trimmed some losses after his comments but continued to trade around 2.73 per dollar, about 1.88 percent weaker from Monday's close.
In Brazil, currency swaps are derivatives that provide protection against losses in the real and mimic an injection of dollars in the futures market.
The sharp depreciation of the real, which touched near 10-year lows on Tuesday, is cited by the bank as one of the main reasons for quickening inflation.
Tombini said the bank will keep an eye on the secondary inflationary effects of a weaker real and rising regulated prices to prevent them from spreading to the rest of the economy.
A sharp drop in global commodities prices and prospects of higher U.S. interests rates next year have put tremendous pressure on the currencies of emerging nations in recent months.
Russia's rouble plunged more than 11 percent against the dollar on Tuesday in its steepest intraday fall since the Russian financial crisis in 1998 as confidence in the central bank evaporated after an ineffective rate hike.
The Russian currency crisis caused a rout in emerging markets as investors fled to less risky assets in developed countries.
Brazil's Tombini repeated that the bank will not be complacent with inflation that should peak in the first quarter of next year, but then start a "long period of decline" toward the 4.5 percent center of the official target.
The central bank stepped up its monetary tightening campaign with a 50-basis-point rate hike on Dec. 3 in a bid to curb above-target inflation and reinforce President Dilma Rousseff's efforts to shift toward more market-friendly policies. (Reporting by Luciana Otoni; Writing Alonso Soto; Editing by Jeffrey Benkoe and W Simon)