The number of South Koreans staying at the joint industrial complex in North Korea declined 20 percent on-year in January following the North's nuclear test, government data showed Wednesday.

The number of South Koreans staying at the Kaesong Industrial Complex in the North reached a daily average of 570 last month, down 20.4 percent from a year earlier, according to the Unification Ministry. It fell 15.3 percent on-month in January.

South Korea has imposed an entry limit of its people to the factory zone in the North's border city of Kaesong to ensure the safety of South Koreans staying there following North Korea's nuclear test on Jan. 6.

The government has only allowed South Korean businessmen directly involved in the operation of factories to enter and stay at the park. Contractors are only allowed into the park if they enter and leave on the same day, it said.

Meanwhile, the number of visits by South Koreans to the complex rose as more Seoul nationals move in and out of the park without staying overnight.

In January, a total of 11,467 South Koreans visited the Kaesong complex for a daily average of 477, up 7 percent from the previous year, according to the data.

"The number of South Koreans' visiting the complex rose as more businessmen and contractors enter the zone and return home on the same day," a government official said "But the number of our nationals staying there decreased compared with the past."

There are concerns that an extension of inter-Korean tension sparked by the North's nuke test may lead to a temporary closure of the complex.

Seoul has said that it is not considering temporarily shutting down the complex or withdrawing South Koreans from it despite the North's provocation. (Yonhap)