The debt-ridden construction company Kumagai Gumi Co. will ask its five major creditors, including Sumitomo Bank and Shinsei Bank, to forgive debts totaling 450 billion yen as part of the firm's rehabilitation plan, company sources said Friday.

The plan also involves halving its capital by about 40 billion yen, asking leading domestic rival Kajima Corp. for a capital injection and slashing about 2,000 jobs, the sources said.

The amount of the proposed debt waiver is one of the largest within the industry, in which a spate of bankruptcies and debt acquittals have been executed since 1997 among midsize companies.