North Korea on Monday extended a deadline by which South Korean firms should pay wages to the North's workers at a joint industrial park in the North, a company official said, amid a months-long row over Pyongyang's unilateral bid to hike the wage.

The North unilaterally decided to raise the minimum wage by 5.18 percent to $74 per month starting in March for North Korean workers employed by the 124 South Korean small- and medium-sized firms at the Kaesong Industrial Complex in the North's border town.

North Korea extended a deadline that falls on Monday until Friday for the Seoul firms to pay March wages for the 53,000 North Korean workers, according to the official at a group of local firms with factories at the complex.

"The North decided to extend the deadline until April 24. None of the South Korean firms have paid the wages," said Yoo Chang-geun, vice president of the group.

The move came as a group of South Korean businessmen made a one-day visit to the industrial park earlier in the day to protest the North's decision following a similar visit on April 7.

Seoul has not accepted the North's unilateral move, saying that Pyongyang violated a 2004 agreement that calls for two quasi-government committees from each side to set the wages together. The wage cap has been set at 5 percent per year.

The two Koreas have held the talks on the wage dispute twice so far through a quasi-government committee, but they failed to produce a breakthrough.

The South's unification ministry reiterated its stance over the issue, calling on North Korea to honor the agreement for the operation of the industrial complex.

"There is no change in Seoul's stance that the wage dispute should be resolved through consultations," Lim Byeong-cheol, spokesman at the unification ministry, said at a press briefing on Monday.

"We plan to come up with measures to minimize any potential damage to South Korean firms, such as providing them with financial compensation," he said.

South Korean firms have been squeezed as the Seoul government has asked them not to accept the North's decision while the North has threatened to collect an arrears charge if they do not pay the higher wages.

South Korea is concerned that the wage row could set a precedent for the North to make unilateral decisions on the operations of the industrial park.

The Kaesong Industrial Complex opened in the early 2000s, the last remaining symbol of inter-Korean reconciliation. It has served as a major revenue source for the cash-strapped communist North. (Yonhap)