Brazil's central bank holds auction to buy dollars

SAO PAULO Jan 15 (Reuters) - Brazil's central bank said on Tuesday it would hold an auction to buy dollars on the spot foreign exchange market as part of an ongoing effort to boost international reserves.

The Brazilian real BRBY, which gained 20 percent in 2007, was 0.86 percent weaker at 1.75 per U.S. dollar shortly after the announcement.

The bank resumed buying dollars in early October after a two-month hiatus from the currency market. It had previously bought greenbacks daily for months, helping lift Brazil's reserves to an all-time high of more than $181 billion. (Reporting by Silvio Cascione, Translated by Elzio Barreto, Editing by Chizu Nomiyama)