Spain's Santander said on Monday it plans to launch a bid in the United States for the remaining 9.4 percent of its Puerto Rico division Santander BanCorp which it does not own.

Spain's biggest bank will offer $12.25 for every share of its Puerto Rican unit in a deal valued at about $50 million.

The offer is expected to be launched within a month with the aim of delisting the unit in New York and from Spain's Latibex exchange.