Lone Star will soon seek to renegotiate its contract to sell Korea Exchange Bank to HSBC, and will ask the British bank to increase its offer beyond the current $6.43bn to reflect the increase in the target's book value, people familiar with the deal said.

The sale contract expires on April 30, but with regulators refusing to approve the deal while legal questions remain, there is no end in sight for South Korea’s longest-running financial soap opera.