Corporate bond sales in South Korea posted a double-digit decline last month as firms issued debts earlier this year on expectations for higher borrowing costs, financial watchdog data showed Tuesday.

Companies raised 10.5 trillion won (9.2 billion U.S. dollars) through bond issuance in August, down 20 percent from a month earlier, according to the Financial Supervisory Service (FSS).

Bonds, issued by industrial companies, tumbled 57.3 percent last month as the bond issuance date for businesses was brought forward on expectations for higher interest rate.

The Bank of Korea (BOK) has kept its benchmark interest rate on hold at an all-time low of 1.25 percent since June last year, but the BOK was widely forecast to raise the rate in the foreseeable future as the U.S. policy rate was lifted to a range of 1.00-1.25 percent.

Bond sales by financial institutions declined 15.7 percent, but the asset-backed securities (ABS) issuance more than doubled due to surging sales in the ABS that securitized monthly smartphone installments as collateral.

From January to August, the corporate bond sales amounted to 107.45 trillion won, up 34.8 percent compared with the same period of last year.