BOGOTA, March 30 (Reuters) - Grupo Aval, Colombia's largest financial conglomerate, spun off its Central American subsidiary BAC Holding International Corp (BHI) on Wednesday, sending shares of the parent diving.

Grupo Aval, controlled by magnate Luis Carlos Sarmiento, said in a statement that it and its other subsidiary Banco de Bogota would keep 75% of direct participation in BHI.

BHI shares were listed on the Colombian and Panamanian stock exchanges as of Wednesday.

Banco de Bogota shares fell 25% after the announcement, to 51,000 pesos ($13.50) on the Colombia exchange, while Grupo Aval shares were down 17.2% at 833 pesos.

Colombia's financial regulator said it had received a request to authorize a public acquisition offer for 5% to 15% of BHI at a price of 293 pesos per share.

The regulator did not identify who made the request, but market agents said Grupo Aval was hoping to increase its shares in BHI.

Neither Grupo Aval nor Banco de Bogota immediately responded to requests for comment.

Grupo Aval also includes banks Banco Popular, Banco AV Villas, Banco de Occidente, Corporacion Financiera Colombiana and pension fund Porvenir.

($1 = 3,765.96 Colombian pesos) (Reporting by Nelson Bocanegra Writing by Julia Symmes Cobb; Editing by Richard Chang)