South Korean companies saw their profitability continue its solid growth in the third quarter of this year, but their sales gains slowed slightly, central bank data showed Thursday.

The ratio of operating profit to sales of non-financial firms in the country reached 7.6 percent in the July-September period, up from 7.4 percent tallied a year ago, according to the data by the Bank of Korea.

At the same time, the pretax net profit margin of South Korean companies rose on-year to 7.2 percent from 6.4 percent.

But their sales expanded 3.5 percent on-year in the three months to September, slowing from 4.8 percent in the previous quarter. The sales growth rate marked 13.8 percent in the third quarter of 2017.

By sector, manufacturing firms posted 6.2 percent on-year growth in sales in the third quarter, while their operating profit rate widened to a record 9.7 percent.

On the other hand, non-manufacturers' sales fell 0.4 percent on-year in the three-month period, with their operating profit margin gaining 4.4 percent.

In particular, third quarter sales in the machinery and electronics sectors increased 8.3 percent on-year, and their operating profit soared a record 18.3 percent.

Chipmaking companies, which have been enjoying booming overseas demand in recent years, are categorized as part of the machinery and electronics sector.

Exports of South Korea-made semiconductors surged 40.2 percent on-year in the third quarter, expanding from a 30.3 percent rise three months earlier.

Sales of the construction sector, however, contracted 6.3 percent in the third quarter, the sharpest on-year decline since

2015 when the BOK started to compile such data. The decline is largely affected by the government-led measures to cool the overheated housing market.

The data was based on a sample survey of 3,333 out of 17,200 companies with 12 billion won ($11 million) in assets from Nov. 7-30. (Yonhap)