HANOI (AP) _ Presidential envoy and Vietnam combat veteran John Vessey met Saturday with Vietnamese officials in an effort to find out what happened to nearly 1,800 Americans still missing from the war.

Vessey, a retired Army general and former chairman of the Joint Chiefs of Staff, is the highest-ranking U.S. emissary to visit Vietnam in 10 years. He came hoping to break a stalemate in the talks on those Missing in Action, or MIAs - an issue this country's communist leaders are trying to link to U.S. humanitarian aid for Vietnamese war victims.

Vessey met for an hour with Foreign Minister Nguyen Co Thach. The session, the first of three possible rounds, produced no official announcements. Talks were to resume Sunday.

The fate of 1,776 Americans listed as missing in Vietnam remains unkown.

''We are here to discuss POW (prisoner of war)-MIA issues, and we hope we can make progress,'' Vessey said upon his arrival earlier at Noi Bai Airport. He did not reply directly when asked if Washington would honor Vietnam's request to discuss Hanoi's war-related humanitarian concerns.

Deputy Foreign Minister Nguyen Dy Nien repeated the request before greeting Vessey. Nien said that while Vietnam was not demanding reparations, officials planned to ask Vessey about possible U.S. aid for the war's victims, including orphans, the disabled and alleged victims of U.S. chemical warfare.

Vietnam, among the world's poorest nations, is desperate for Western aid. It has hinted that Vessey likely will go home empty-handed unless the issue is addressed.

Washington has said Vessey will discuss MIAs and humanitarian issues including the release of Vietnamese prisoners from re-education camps and the resettlement of Amerasians - children fathered by Americans during the war, which ended in 1975.

Foreign Minister Thach, asked before the talks about the possibility of Washington opening an office in Hanoi to handle MIA matters, said the idea was fine in principle. If Vessey raised it, he added, ''I will also raise my desire to have such (an) office in Washington, too.''

Washington has said it will open an office only if progress on MIAs merits the move.

Also Saturday, Gen. Tran Cong Man, editor of the army newspaper Quan Doi Nan Dhan, told foreign journalists that Vietnam would welcome humanitarian aid from Washington.

He acknowledged the suffering of the families of American MIAs. But he also said, ''We Vietnamese are suffering too, and perhaps our suffering is much greater. Almost every family in Vietnam has a person who is an MIA.''

About 2.7 million U.S. soldiers served in Vietnam, of whom 58,000 died. Vietnamese officials have said that half of the two million Vietnamese servicemen and civilians who died in the war remain unaccounted for.

Washington maintains an embargo on aid and trade with Vietnam and says it won't change its policy until Hanoi gives the ''fullest possible accounting'' on MIAs and withdraws its more than 100,000 troops from neighboring Cambodia.

''Humanitarian reciprocity is one thing, but any attempt to trade information on our missing men for economic aid is another,'' Secretary of State George Shultz said recently in response to Vietnam's request. ''We cannot agree to this.''

Beginning in early 1985, Hanoi returned large numbers of American remains, cooperated in the first joint excavation of a U.S. warplane crash site and agreed to investigate reports of Americans sighted in Vietnam since the war.

Hanoi has returned no remains since Nov. 26, 1986, and U.S. and Vietnamese technical experts have not met since October, although they were to meet six times a year.

Vessey, who was decorated for heroism in Vietnam combat, is the highest- ranking envoy to visit since former United Auto Workers Union President Leonard Woodcock came as President Jimmy Carter's emissary in 1977. Woodcock returned with no lasting agreements.

Vessey's seven-member delegation includes David Lambertson, the deputy assistant secretary of state for East Asian and Pacific affairs, Richard Childress of the National Security Council and Ann Mills Griffiths, director of the National League of POW-MIA Families.