SAO PAULO, March 17 (Reuters) - Brazil's central bank called an auction on Wednesday to buy U.S. dollars on the spot foreign exchange market as part of an ongoing effort to boost international reserves and limit currency market volatility.

Brazil's currency, the real (BRBY), was trading 0.17 percent stronger at 1.765 per dollar shortly after the announcement. (Reporting by Jose de Castro; Writing by Luciana Lopez; Editing by Dan Grebler)