North and South Korea have begun a trial reopening of the Kaesong industrial park after a five-month standoff.

Vehicles carrying South Korean workers entered the joint industrial zone, which sits on the border between the two countries, as they continue to negotiate on the economic venture.

Seoul's unification ministry said more than half of the 123 South Korean companies based in the zone will resume operations as part of the trial.

North Korean workers have already started reporting to work, according to local reports.

The inter-Korean industrial park employs more than 50,000 North Koreans and is a key contributor to Pyongyang's revenue.

More than 800 South Korean managers and workers are expected to cross the border on the reopening day, according to the Yonhap news agency. Nearly half of them are likely to stay overnight.

Many South Korean businessmen have expressed optimism over the breakthrough, although some of them remain tense.

"Honestly, I still feel a bit nervous, because you never know whether the North will change its mind in the future. Who knows if a crisis like this won't happen again?" a textile company manager told AFP.

Operations at the industrial park, the only inter-Korean commercial project still in operation, resume following a series of talks between top delegates from the neighbouring countries.

North Korea withdrew its workers in April 2013, after North Korea's third nuclear test led to a marked deterioration in relations.

In addition to reopening the Kaesong complex, North and South Korea have created a management committee to ensure the smooth, sustainable operation of the facility.

Kim Ki-Woong, co-chairperson of the joint committee, hopes the joint venture becomes internationally competitive.

"To reach this goal, there are still quite a few problems to resolve, even though the factory park itself has reopened," he said before heading to Kaesong.