The €2.85bn deal will expand the French gas giant's presence in Asia; the acquisition is being financed by a bridge loan and will be (re)financed by bond issues.
South Korea's president has lifted martial law after parliament voted to defy the shock move on Tuesday; Bank of Korea held an emergency meeting on December 4.
Regazzoni was previously the bank's global head of multinational corporate coverage, Corporate and Institutional Banking (CIB), based at its Paris headquarters.