HANOI, AUG. 1 -- President Reagan's special envoy today began talks on renewing stalled efforts to account for the nearly 1,800 American servicemen still missing from the Vietnam War.

Retired Army general John W. Vessey Jr., a former chairman of the Joint Chiefs of Staff and combat soldier decorated for heroism in Vietnam, held his first meeting with Vietnamese officials this afternoon. There was no indication from American or Vietnamese participants whether any progress had been made. Vietnamese officials said another round of talks is scheduled for Sunday, with a third session planned for Monday if both sides agree it is necessary.

"We are here to discuss POW/MIA {prisoner of war/missing in action} issues, and we hope we can make progress," Vessey said upon his arrival here. Asked if he were carrying new proposals to break the impasse on the issue, Vessey said, without elaborating, "The solution lies here" in Hanoi.

{Deputy Foreign Minister Nguyen Dy Nien, who greeted Vessey at the airport, told reporters that, in exchange for Vietnam's help in tracing the missing Americans, the United States has agreed to consider giving humanitarian aid to the war's victims, including orphans, disabled people and victims of alleged U.S. chemical warfare, Reuter reported. Nien said war reparations would not be discussed during Vessey's visit.

{"We have agreed we will discuss humanitarian issues," Reuter quoted Vessey as saying.}

Vessey's nine-member team is the highest ranking American delegation to visit Vietnam since President Carter sent labor leader Leonard Woodcock to Hanoi 10 years ago for talks on MIAs and establishing diplomatic relations. Vessey's Vietnamese counterpart in the talks is Foreign Minister Nguyen Co Thach.

In 1985, Vietnam pledged to settle the MIA question within two years, but has not returned any MIA remains since mid-1986 and has not agreed to any technical talks on the subject since October.

Vietnamese officials have said they want U.S. aid in return for their efforts to trace the missing Americans. But the United States rejects any attempt to link political or economic concessions to the MIA issue.

"Humanitarian reciprocity is one thing, "but any attempt to trade information of our missing men for economic aid is another. We cannot agree to this," Secretary of State George P. Shultz said in a speech to MIA families meeting in Washington two weeks ago.

Thach said last month that Vietnam intended to raise a variety of humanitarian concerns with Vessey, including human suffering and damage caused by the war. "If we can help the Americans on MIAs, then the Americans can help us heal the wounds of war," Thach said.

Other members of Vessey's delegation include Gen. Robert Kingston, a former head of a military unit that analyzes remains and cases of missing Americans; David Lambertson, deputy assistant Secretary of State for Asia and the Pacific; and Ann Mills Griffiths, director of the National League of Families of the missing servicemen.