A nuclear test carried out by North Korea on Monday has caused no problem to overland travel to or from the jointly operated industrial complex in the North Korean border city of Gaeseong.

The North conducted a nuclear test in the town of Punggye in the northeastern part of the country on Monday.

The Unification Ministry said the North sent a message to Seoul at around 8:30 a.m. Tuesday permitting cross-border passage.

About 640 South Korean Gaeseong workers crossed the border into the North on Tuesday morning, and some 380 South Koreans will return home from the industrial complex in the afternoon.

The government has placed travel restrictions on North Korean regions other than the Gaeseong Industrial Complex and the Mount Geumgang resort in the wake of Pyongyang’s second nuclear test.

The North’s first detonation of a nuclear device came in October 2006.