Banco Bilbao Vizcaya Argentaria SA, Spain's second-biggest bank, agreed to pay about 1 billion euros ($1.51 billion) to boost its investment in China's State-owned CITIC Group to strengthen its foothold in Asia.

BBVA exercised an option to buy an additional 4.93 percent in China CITIC Bank to bring its holding in the lender to 15 percent, the Bilbao, Spain-based company said in a filing to regulators. BBVA paid HK$6.45 (83 cents) per share for the stake, the bank said.

The bank agreed three years ago to buy stakes in CITIC Group companies for 989 million euros, acquiring an initial 5-percent stake in CITIC Bank, and 15 percent of CITIC International Financial Holdings Ltd as it targets China to diversify revenue.

BBVA has now boosted its investment in CITIC to 3 billion euros as government stimulus and growing credit revives growth in the world's third-largest economy. The Spanish bank is also seeking to benefit from trade flows between China and Latin America.

"It's probably a good option for them over the long term," said Arturo de Frias, a banking analyst at Evolution Securities in London. "For now it doesn't really move the needle for BBVA in terms of profit or valuation."

BBVA will buy 1.9 billion China CITIC shares from CITIC Group, according to CITIC Bank's statement to the Hong Kong Stock Exchange yesterday. BBVA and CITIC signed accords to develop car financing and private-banking business as they also collaborate on corporate banking and trade finance.

CITIC Group's stake in CITIC Bank will drop to 62.3 percent after the transaction. BBVA's stake in CITIC International, another CITIC unit, stands at 30 percent.

CITIC Bank rose 0.6 percent to HK$6.67 in Hong Kong trading.