Inter-Korean overland travel to the jointly operated Gaeseong Industrial Complex started later than usual Thursday.

The delay was due to North Korea granting passage permission to South Korea one hour later than expected.

The Unification Ministry said the permits were received at 10 a.m. Thursday. Cross-border travel commenced 15 minutes later.

Some 700 South Koreans left for the industrial zone Thursday with 540 expected to return later in the day.

Ten heads of South Korean companies operating in the industrial complex will return to the South at 3 p.m. Thursday after wrapping up a visit to the North. During the visit, North Korean authorities were urged to guarantee free business activity to South Korean companies doing business in the industrial park.