"Preparations continue" to receive the remains, the US official told AFP on condition of anonymity. "It could happen in the next few days."

The US and North Korean leaders agreed to the repatriations during their historic June 12 summit in Singapore.

"On several occasions in the past, DPRK officials have indicated they possess as many as 200 sets of remains they had recovered over the years," the Pentagon said in factsheet updated Monday about those reported missing in action during the Korean War of 1950-1953.

"The commitment established within the Joint Statement between President Trump and Chairman Kim would repatriate these as was done in the early 1990s and would reinforce the humanitarian aspects of this mission."

The document used the acronym for North Korea's formal name.

More than 35,000 Americans were killed on the Korean Peninsula during the war, which ended in an armistice with no peace treaty.

Among them, 7,700 are still considered missing, including 5,300 in North Korea alone, according to the Pentagon.

Between 1990 and 2005, the United States was granted the repatriation of 229 sets of remains from the North under an earlier agreement that was subsequently suspended when ties between the two countries deteriorated.