SAO PAULO, July 31 (Reuters) - Brazil's central bank has authorized testing of payments via Facebook Inc's messaging service WhatsApp in the country, Visa Inc and Mastercard Inc said on Friday.

Mastercard said in a statement that the tests would allow a limited number of cards to make small payments. WhatsApp initially launched its payments service on June 15, but was later blocked by Brazilian authorities, citing fair competition and data privacy concerns. (Reporting by Aluisio Alves in Sao Paulo Editing by Matthew Lewis)