After months of negotiations, the 15 creditor banks of ailing general contractor Kumagai Gumi Co. have basically agreed to a debt-waiver package that would relieve the firm of a loan burden totaling 450 billion yen, sources close to the talks said Wednesday.

According to the sources, the agreement was reached after Kumagai Gumi's main creditor, Sumitomo Bank, agreed to up its share of the debt-wavier plan by roughly 30 billion yen from its initial pledge of 234 billion yen.

In addition, the midsize construction firm will securitize a portion of its borrowings from 13 financial institutions, including several regional banks, in a debt-equity swap, the sources said.