SEOUL, April 29 (Yonhap) -- South Korean companies at a joint inter-Korean industrial complex in the North Korean city of Kaesong had shown steady sales growth before production there ground to a halt early this month, data showed Monday.

The average sales by 118 out of a total of 123 South Korean firms operating in the complex came to 1.48 billion won (US$1.3 million) in 2011, compared with 1.13 billion won in 2010 and 900 million won in 2009, according to the data by state-run Small and Medium Business Corp.