Cathay Financial Holding Co Ltd said it was open to raising its stake in Rizal Commercial Banking Corp (RCBC) to as much as 30 percent, soon after it acquired 20 percent of the mid-sized Philippine lender.

The two companies on Wednesday sealed the deal for Cathay Financial to acquire 20 percent of RCBC for 17.92 billion pesos ($400 million), a sign that Taiwanese financial firms are moving more aggressively to expand beyond their home market.

Cathay Financial President Lee Chang-Ken said the company had obtained the management's approval to acquire more RCBC shares from the open market.

"If they (RCBC) agree...definitely we are interested to invest more," Lee told reporters when asked if the company was looking to acquire more shares in the Philippine lender.

Lee said current the share price of RCBC, the Philippines' ninth largest lender by assets, is attractive compared with when the deal was announced in September.

Shares in RCBC rose 1.08 percent to 46.80 pesos each on Wednesday, 26.9 percent lower than the 64 peso buying price of Cathay Financial.

Taiwan's regulators encourage financial institutions to expand in Asia given an overcrowded home market. For their part, Philippine banks are drawing overseas interest after Congress passed a law allowing foreign groups to take full control of local banks.

"Both RCBC and Cathay see a sizeable cooperation opportunity in the asset management space in the Philippines," RCBC said in a statement.

The Philippine lender is also tapping into the retail and consumer banking expertise of Cathay Financial subsidiary Cathay United Bank, said RCBC President Lorenzo Tan.