Brazil's central bank calls auction to buy dollars

SAO PAULO Oct 28 (Reuters) - Brazil's central bank offered to buy dollars on the spot foreign exchange market on Wednesday in an ongoing effort to boost international reserves and soak up greenbacks pouring into the economy.

The bank has bought about $20.78 billion on the spot market since May 8, including $6.518 billion this month through Oct. 23, to soak up dollar liquidity and prevent further appreciation of Brazil's currency, the real.

Brazil's currency, the real BRBY, was trading 0.17 percent weaker at 1.742 per U.S. dollar shortly after the central bank's announcement. (Reporting by Silvio Cascione; Writing by Luciana Lopez; Editing by James Dalgleish)