Several US regulatory agencies are investigating the Florida unit of Banco Espírito Santo, according to bank officials, the latest front in a sprawling multinational effort to untangle the finances behind the collapsed Portuguese business empire.

The Securities and Exchange Commission and the Federal Deposit Insurance Corp, along with Florida's financial regulator and a Wall Street self-regulatory organisation, are looking into the Miami-based bank's business with an Espírito Santo bank in Panama, according to the bank officials. Virtually all of the Panama bank's business was with various parts of the Espírito Santo group and family, according to Panama's financial regulator, which seized the bank in July.