Several weeks ago it offered to buy Kumho Asiana's holding at a 30% premium to the market price.

ECONOMIST: Restructuring South Korea's chaebol

Regulators say that they have been urging banks to take a hard line with nine struggling chaebol, including Kumho Asiana.

ECONOMIST: Restructuring South Korea's chaebol

In addition to Daewoo, Kumho Asiana owns Asiana, the country's second-biggest airline, and petrochemical, tyre, life-insurance, resort and transport businesses.

ECONOMIST: Restructuring South Korea's chaebol

That would still leave Kumho Asiana about 1.7 trillion won short of its obligations under the put option, according to CLSA, a broker.

ECONOMIST: Restructuring South Korea's chaebol

So Kumho Asiana needs to find another 4 trillion won.

ECONOMIST: Restructuring South Korea's chaebol