North Korea said Saturday it shot down an "enemy" helicopter that it claimed illegally flew over its airspace.

In Seoul, the national Yonhap news agency said a U.S. military helicopter crash-landed in North Korea after crossing the heavily armed Korean border around mid-morning Saturday.Quoting an unidentified military source, Yonhap said neither of the two crewmen aboard the OH-58 helicopter appeared injured.

Pentagon officials in Washington had no immediate comment, saying they were attempting to verify exactly what happened.

The North's Korea Central News Agency, monitored in Seoul, said the helicopter "was brought down at one shot in the area of our side in a self-defensive measure."

The helicopter was shot down near Ipho-ri in North Korea's eastern front line, it said, adding that North Korean officials were investigating the illegal intrusion.

The South Korean news agency said the helicopter crash-landed about three miles north of the northern sector of the 2.5-mile-wide Demilitarized Zone that has separated the capitalist South and the communist North since the end of the 1950-53 Korean War.

The small, two-seater helicopter was on a routine reconnaissance mission, Yonhap said.