A U.S.-based environmental group in April visited the northern part of the Demilitarized Zone dividing the two Koreas.

Kim Gye-jeong, the head of the DMZ Forum, told Radio Free Asia Wednesday that North Korea permitted his group to visit the zone in April for an onsite inspection.

The forum is an international NGO devoted to the preservation of the DMZ.

Kim said the forum seeks to launch the "Beijing Project" aimed at preserving cranes and black-faced spoonbills found in Cheolwon, Gangwon Province, around the border area.

He said Pyongyang allowed the April visit on condition that the NGO focus on habitat preservation in the DMZ.