The operating profit ratio of South Korean manufacturers hit a record high in the second quarter on brisk chip export, central bank data showed Thursday.

The ratio of operating profit to revenue for 3,333 companies subject to external audit averaged 7.7 percent in the April-June quarter, according to the Bank of Korea (BOK).

It was the highest since the bank began compiling the data in 2015. It was attributable to solid shipment of locally-made semiconductors, which led to the record-high profit ratio among manufacturers.

The operating profit-to-sales ratio for manufacturers recorded a new quarter high of 9.5 percent in the June quarter, after posting 8.8 percent in the previous quarter.

Excluding key chipmakers, such as Samsung Electronics and SK Hynix, the ratio for manufacturers fell to 6 percent.

The ratio of operating profit to revenue among non-manufacturers slid to 5 percent in the second quarter from 5.3 percent a year earlier.

Revenue among manufacturers rose 4.3 percent in the second quarter, higher than a 3.4 percent growth in the prior quarter.

Sales growth among non-manufacturers accelerated to 5.5 percent in the second quarter from 3.4 percent in the previous quarter.