MADRID, April 20 (Reuters) - Spain’s Caixabank seeks to cut 8,291 jobs and close 1,534 branches in Spain as part of a cost-savings plan following the acquisition of rival Bankia, a spokesman for the union Comisiones Obreras (CCOO) said on Tuesday. Caixabank, which last month closed the 4.3 billion deal to create Spain’s biggest domestic bank, was not immediately available for comment. (Reporting by Jesús Aguado and Emma Pinedo; editing by Inti Landauro)