South Korea's unification ministry issued a strongly-worded statement Monday against North Korea's attitude on their joint venture in Kaesong, calling again for immediate dialogue to resolve pending problems.

It's "deeply regrettable" that the North is not responding to Seoul's offer of talks to discuss Pyongyang's unilateral decision to raise wages for its workers at the Kaesong Industrial Complex, said the ministry.

"It's questionable whether (the North) has the will for the development of the complex as the two sides agreed," its spokesman Lim Byeong-choel said, reading out the statement at a press briefing.

The North is violating an inter-Korean agreement and rules to decide all issues related to the operation of the Kaesong zone, including working conditions, added Lim.

Last month, the communist nation announced a 5.18-percent hike in the minimum wage for its workers in the zone to US$74 a month starting in March.

"The government can never accept such a unilateral measure by North Korea," the official said. "The government will take every necessary step for the development of the Kaesong Industrial Complex and the protection of (the South's) firms there."

He urged Pyongyang to hold talks with the South on Friday as proposed.

Launched in 2004 in the North's border town, the zone is home to about 120 South Korean firms, mostly small and medium-sized, which employ more than 53,000 North Korean workers.

The South's government has advised the companies not to comply with the North's decision on the wage level. (Yonhap)