U.S. military experts will travel to Hanoi Sunday to begin the most extensive joint searches ever for American MIAs in Vietnam and Laos, a U.S. Embassy spokesman said Saturday.

Two separate American teams will undertake "investigative, survey and excavation activities" with Vietnamese and Lao counterparts, said spokesman Ross Petzing.The teams, including officials from the military's Joint Casualty Resolution Center and the Army Central Identification Laboratory, are due to arrive in Hanoi Sunday on a U.S. Air Force C-141 transport jet carrying vehicles and special equipment, he said.

The only previous joint excavation for the remains of missing Americans in Vietnam came in 1985, but that was focused on a single airplane crash site.

The search in Vietnam will begin Sunday and last through Oct. 5. It will cover a broad area, including a number of locations north of Hanoi.

A second American team will depart Hanoi Tuesday for Vientiane, the capital of Laos, to conduct similar investigations for four days.

The investigations will focus on some of the 70 highest-priority "discrepancy cases," Petzing said. These are cases in which the United States has evidence that Americans were captured alive.