Washington's ambassador to South Korea calls a diplomatic excursion he took to a joint an industrial park in North Korea "useful." He says President Bush's special envoy for North Korean human rights, who has criticized the venture, may make a visit of his own soon.

U.S. Ambassador to South Korea Alexander Vershbow, who earlier this year described North Korea as a "criminal regime," joined fellow international envoys Monday in a visit to the North's Kaesong industrial park.

The park, built by South Korea, is a centerpiece of Seoul's policy of economic cooperation with Pyongyang. It offers South Korean companies the opportunity to use inexpensive North Korean labor, mainly for low-skilled manufacturing.

Vershbow took Monday's tour along with about 80 other senior international diplomats. He describes the excursion as "very interesting."

"This visit was very useful in gaining more information about Kaesong, which I will pass on to my colleagues in Washington," he said. "There are still some questions that people have in their minds about Kaesong, and I hope that the information I pass back will be helpful to my colleagues."

Among those colleagues is Jay Lefkowitz, President Bush's envoy for North Korean human rights. Lefkowitz received sharply worded rebukes from South Korean officials last month after he suggested workers in Kaesong may be exploited. Vershbow says talks are underway for Lefkowitz to make his own Kaesong visit, probably next month.

"I think that he [Lefkowitz] is very interested in also gaining his own first hand impressions of Kaesong," added Vershbow.

South Korean officials say companies pay a North Korean labor agency about 50 dollars a month for each worker at Kaesong. However, there is no confirmation of how much money the workers actually receive.

Lefkowitz has called for international monitoring of Kaesong by a body such as the International Labor Organization to make sure workers are treated fairly.

South Korean Foreign Minister Ban Ki-moon took part in the visit, in his first trip to North Korea since assuming his post. Ban says even though there is "room for improvement" in Kaesong, the industrial park holds lessons for the diplomatic community.

Ban says Kaesong is a symbol not just of inter-Korean unity, but a model for international reconciliation and cooperation in general.

The Kaesong park is a sticking point in free trade talks between South Korea and the United States. Seoul wants a trade agreement to treat Kaesong-produced goods as originating from South Korea, an idea Washington has so far rejected.

Peter Beck, who monitors Korean issues for the International Crisis Group, a research organization, says Monday's visit was probably not aimed at the trade talks.

"I think there's a realization here in Seoul deep down that Washington is not going to budge on this issue [trade]," noted Beck. "So I think it's really directed more toward shaping broader U.S. opinion about Kaesong."

Beck says the Kaesong visits also are partly aimed at defusing a climate of confrontation between the United States and North Korea, which has worsened over Pyongyang's refusal to return to negotiations aimed at ending its nuclear weapons programs.