MADRID, May 6 (Reuters) - The board of Spain's Banco Sabadell on Monday rejected a merger proposal by larger rival BBVA for a 12 billion euro ($12.93 billion) all-share merger, La Vanguardia newspaper cited unidentified sources as saying.

Sabadell officials were not immediately available for a comment. (Reporting by Joan Faus and Jesus Aguado, editing by Andrei Khalip)