The third White House Conference on Aging ended yesterday as it began--in controversy, amid charges of manipulation for partisan purposes.

The renewed allegations were fueled by documents purporting to show that the conference's key committees had been stacked with pro-administration delegates and that the administration had employed the techniques of a political convention to organize its forces.

Despite these charges, critics of the administration at the four-day decennial conference expressed satisfaction with the general thrust of the approximately 600 resolutions approved at its final session.

On Social Security and related programs--the dominant issue at this conference--the delegates generally opposed any further cuts in Social Security benefits for present recipients and favored efforts to maintain those benefit levels for future recipients. They also favored the elimination of any mandatory retirement age and the expansion of Medicare benefits.

From the outset, the conference has been plagued by charges--primarily from the leadership of organizations representing the elderly--that the administration was attempting to prevent passage of resolutions conflicting with its policies. One of the documents that surfaced yesterday was a copy of a Sept. 18 letter from an aide to Republican Gov. William P. Clements of Texas to Betty Heitman, co-chairman of the Republican National Committee.

The letter, sent along with a list of the Texas delegates to the conference, states that there are "only four of them, marked with an asterisk, who would put loyalty to the president ahead of their commitment to the elderly and who would not take offense at the involvement of the Republican Party."

Other documents listed conference committee members as "favorables, not favorables and not identified."

Another partial set of documents listed a whip and deputy whips for certain committees, including the key Social Security committee. The whip of that committee was listed as Bruce Nestande, an Orange County, Calif., supervisor who served as an aide to President Reagan when he was California governor.

Nestande and other officials, including Heitman and Health and Human Services Secretary Richard S. Schweiker's top assistant, David Newhall III, denied that any effort had been made by the administration to manipulate the conference.

Nestande, appointed a delegate to the conference approximately six weeks ago by the administration, acknowledged that he was the whip on his committee, "if you want to call it that," but insisted that he had taken on the task without being asked and that he had reported to no one in the administration.

Nestande was the author of a resolution opposing use of general revenue funds to support Social Security, which reflected the administration's position and was strongly opposed by leaders of organizations for the aging. When the resolution passed 111-34, "I was rather surprised," Nestande said.

Newhall denied in a press conference that the documents had come from HHS or the White House Conference. Although he conceded that on two or three occasions he had directly intervened in the conference, he denied that he was directing it behind the scenes or manipulating committees to ensure passage of pro-administration resolutions.

As for the purported whip system, Newhall said, "I would assume that every group with a strong viewpoint made an effort to organize. I would imagine there were six or seven whip systems representing people with divergent viewpoints."

Jack Ossofsky, spokesman for a consortium of groups representing more than 16 million older persons, said that his groups had been successful in passing their resolutions "in spite of what they tried to do to us. We still won. The results of this conference are still basically good, overwhelmingly good."

Rep. Claude Pepper (D-Fla.), an honorary chairman of the conference and an early critic of the administration's handling of it, also praised the outcome.

"Democracy has a way of rising to its proper height," he said. "There may have been some influence in the early days that I didn't like, but it all sort of came out in the wash."