SEOUL, South Korea (AP) _ American pilot Bobby Hall spent Christmas in captivity, ending U.S. hopes that North Korea would free him for the holiday.

U.N. military officials held a low-level meeting at the truce village of Panmunjom on Sunday with officers of the Korean People's Army. No details were available.

''However, we continue to work through the processes which we hope will lead to a senior officers' meeting as soon as possible,'' said Jim Coles, a spokesman for the U.S. and U.N. military presence in South Korea.

The meeting was between joint duty officers on both sides of the Demilitarized Zone that separates the two Koreas. The duty officers usually have daily contact, but reportedly have not discussed the issue of Hall's release in days.

Final details for the repatriation of the body of Hall's colleague, Chief Warrant Officer David Hilemon, were worked out during a generals' meeting on Wednesday.

Hilemon was killed when the OH-58C helicopter either crashed or was shot down on Dec. 17. His body was returned Thursday. Hall was taken captive.

As part of its efforts to gain Hall's release, the United States was to send Pyongyang an official letter of regret for the straying of his Army helicopter over North Korean territory one week ago, U.S. sources said.

The South Korean newspaper Dong-a Ilbo reported Sunday that the letter already had been sent. Coles said he could not confirm that.

But in Washington, a White House official speaking on condition of anonymity confirmed Saturday night that a letter had been sent to the North Koreans. The official declined to characterize its contents.

Military officials have told North Korea that the helicopter flown by Chief Warrant Officers Hall and David Hilemon strayed into North Korea due to a map- reading error, Rep. Bill Richardson, D-N.M., said Saturday.

Hilemon was killed when the OH-58C helicopter either crashed or was shot down Dec. 17. His body was returned Thursday. Hall was taken captive.

Richardson told NBC News there were ''very good signs'' in Saturday's meeting at the Korean War truce village at Panmunjom. He noted that high-level U.S. military officials were involved, as North Korea wanted.

Richardson, who happened to be in North Korea at the time, helped negotiate the repatriation of Hilemon's body.

He said the United States is giving information to North Korea that will allow Pyongyang to be ''convinced that it was not an intelligence mission.''

Earlier Saturday there were conflicting reports on whether Hall would be freed by Sunday.

South Korea's Yonhap News Agency first reported that a deal had been reached to free Hall on Christmas Day, but then backtracked and said that was unlikely.

U.S. officials in Korea and at the Pentagon cast doubts on the report that Hall would be freed on Sunday.

U.N. officials said they still were seeking to talk with the North to ''resolve issues'' on the release. In a statement, the U.N. Joint Forces Command said it also has requested details on Hall's condition.

''The KPA (Korean People's Army) has claimed that their investigation into this incident is still under way and Chief Warrant Officer Hall will be returned once it is completed,'' the U.S.-led command said.

Pyongyang has said Hall is in good health. No contact is being allowed with him.

The incident had threatened to damage relations between Washington and Pyongyang, which have improved since they signed a nuclear accord two months ago. The United States also is seeking the return of the OH-58C helicopter.

North Korean officials have said the helicopter was on a spy mission and was shot down. U.S. officials say it was on an unarmed training mission.

The last radio contact with the helicopter indicated the pilot believed he was still in South Korea, when in fact he was about 3 1/2 miles into North Korean territory, according to the Pentagon.

U.S. officials say the pilots may have been disoriented by heavy snow that covered navigational placards on the ground and made landmarks difficult to identify.