MADRID, June 20 (Reuters) - Shareholders in Spain's housing developer Metrovacesa owning just 11.47% of its capital have a accepted a tender offer by Mexican billionaire Carlos Slim's Spanish construction firm FCC for a 24% chunk of the company, the CNMV market supervisor said.

Slim had sought to sharply increase his 5.5% stake in Metrovacesa via the 284 million-euro ($312.29 million) partial bid and rival the two key shareholders, Spanish banks Santander and BBVA, with 49.4% and 20.8%, respectively.

FCC did not immediately reply to a request for comment on whether it would proceed with the acquisition of the additional stake that would lift Slim's total share of the company to 16.87%.

Slim, whose net worth has been estimated at $62 billion by Forbes magazine, has been betting on Spanish real estate and infrastructure. His holding company, Inversora de Carso, also controls real estate developer Realia.

(Reporting by Corina Pons, editing by Andrei Khalip)