Britain's biggest bank is in talks with Lone Star, a private equity firm, to buy 51 per cent of KEB, South Korea's sixth-biggest bank, to plug a major gap in its Asian presence. The price could be around the $6bn (£3bn) mark, making it potentially HSBC's biggest Asian acquisition since it bought Hang Seng Bank in 1965.

HSBC has missed out in South Korea before, leaving Citigroup of the US to buy Koram Bank in 2004 and allowing the UK's Standard Chartered to outbid it for Korea First Bank the following year. HSBC makes almost half its profit in Asia, where it was founded in 1865, but has spent recent years building up in the US, where it has been hit by losses in the sub-prime mortgage market. Stephen Green, the bank's chairman, is now looking for growth in Asia and has said he is prepared to make acquisitions to bolster its position as the region's biggest international bank.

Mike Trippitt, an analyst at Oriel Securities, said: "I see it as a positive but they really should have done this two years ago. The bottom line is Korea is a very large economy in Asia and fast-growing and they need to be in it."

South Korea's economy is booming, with exports surging in the second quarter of this year, consumer confidence rising and unemployment falling. The country is home to some of Asia's biggest companies, including the electronics manufacturers Samsung and LG and the car maker Hyundai, and is a major trading partner with China, where HSBC is the biggest international bank. HSBC is prepared to pursue a riskier deal than it would normally to secure the last major South Korean bank available to it. The acquisition could be complicated by legal problems, with Korean prosecutors accusing Lone Star of colluding with bureaucrats to buy the bank on the cheap in 2003. There has been simmering unrest in South Korea about foreign companies buying key Korean businesses.

HSBC has been in Korea since 1897 and operates 11 branches and four commercial banking centres.

KEB's main focus is on commercial banking, and it is South Korea's biggest bank for trade finance and foreign exchange. HSBC would look to drive more business through these divisions and to sell extra retail banking products through KEB's 352 branches to build on the Korean lender's relatively small 2.6 per cent share of retail banking. KEB was founded in 1967 and has more than 5,000 employees. HSBC would keep KEB's name, an HSBC spokesman said.