North Korea warned Monday that the untended remains of US servicemen killed in the Korean War were being "carried away" by giant infrastructure projects and blamed Washington for suspending efforts for their recovery.

Close to 8,000 Americans remain unaccounted for from the 1950-53 Korean conflict, according to the US Defence Department.

"Many remains have been left uncared for and have been carried away en masse," said a spokesman for the North's military delegation in the border truce village of Panmunjom.

In a written statement, the spokesman said the displacement of the remains was largely due to construction work surrounding major development projects, including hydro-electric power stations.

From 1996 North Korean and US military teams conducted 33 joint recovery missions and recovered 225 sets of remains, but the process was halted in 2005 by then-defence secretary Donald Rumsfeld who felt the safety of US teams could not be guaranteed amid rising nuclear tensions.

The two sides agreed in 2011 to resume the joint missions, but the US scrapped the plan to protest North Korea's decision to push ahead with a space rocket launch seen as a disguised ballistic missile test.

"History will curse and condemn the US administration ... for scuttling such humanitarian work," the North Korean spokesman said.

A US military spokesman in South Korea dismissed the statement as "one of North Korea's usual accusations".

Pyongyang has previously used the issue of missing servicemen to try to entice Washington into two-way talks.

The cash-strapped North reportedly earned millions of dollars for cooperating in the past with the recovery of remains.