A Unification Ministry official has refuted criticism of an inter-Korean business complex by special U.S. envoy for North Korea's human rights Jay Lefkowitz.

In a contribution published in the Wall Street Journal Thursday, policy and public relations director Lee Gwan-se said North Korean workers at the Gaesong Industrial Complex earn more than 57 dollars a month, twice the average wage in North Korea.

He also said working conditions at the complex meet standards of the International Labor Organization.

In an article published last week, Lefkowitz questioned the wages and conditions of North Korean workers at the complex and the lack of monitoring of Seoul's humanitarian aid to the North.