The effort saw the remains of more than 50 US servicemen killed in the 1950s Korean war handed over by North Korea last year in a sign of improved relations between Donald Trump and Kim Jong Un.

But communications on the program halted after the two leaders failed to make progress in talks on North Korea's nuclear program in their February summit in Hanoi, according to Chuck Prichard, a spokesman for the Defense POW/MIA Accounting Agency (DPAA).

North Korean officials "have not communicated with DPAA since the Hanoi Summit," Prichard said in a statement.

"As a result, our efforts to communicate with the Korean People's Army regarding the possible resumption of joint recovery operations for 2019 has been suspended."

"We have reached the point where we can no longer effectively plan, coordinate, and conduct field operations" with North Korea, he said.

In July 2018 Pyongyang handed over the remains of more than 50 American servicemen who were lost in North Korea territory during the Korean War of 1950-1953.

The return of the remains marked the partial fulfilment of an agreement reached between Trump and Kim at their historic initial summit in Singapore in June 2018.

The White House at the time called it "a significant first step" in the process of searching for an estimated 7,700 Americans considered still missing from the war, of which 5,300 were believed lost in North Korea.