The Reagan administration is divided on whether to ask Congress for additional military aid to El Salvador for this fiscal year, torn between a desire to strengthen the government there and a desire to cut federal spending. The controversial issue yesterday even appeared to confuse White House spokesman Larry Speakes.

Responding to questions, Speakes said the administration will ask Congress for more such aid, "following the Kissinger commission recommendations" for a five-year, $8 billion program of economic and military aid to Central America to bolster it against communism.

Speakes appeared to indicate that the administration would ask this year for perhaps as much as $72 million in supplemental military aid and $100 million in economic help for El Salvador.

Administration officials later denied that interpretation.

"There isn't any supplemental that's approved around here," nor is there any decision to ask for one, a high-ranking official said. "We want a bit more than last year, but that's for fiscal 1986."

The official said a $200 million figure mentioned by Speakes as a possible military aid request was "higher than I would expect" any increase to be for 1986 but might resemble the combined total for fiscal 1986 and a supplemental 1985 request, if there were one.

"I guess he didn't study the figures closely," the official said.

Other officials said that Langhorne A. (Tony) Motley, assistant secretary of state for inter-American affairs, and U.S. Ambassador to El Salvador Thomas R. Pickering had urged the White House to request supplemental 1985 funding but that administration budget-watchers vetoed the idea as premature until Congress acts on emergency-aid requests for African famine relief.

Pickering and Motley are said to be concerned at Salvadoran President Jose Napoleon Duarte's lack of progress in implementing promises made before he was elected last May. He has encountered resistance on proposed legislation from rightist elements that dominate the Salvadoran legislature.

There has been no movement toward accord with the Salvadoran left, despite much-publicized talks that began last October, and the civil war death toll mounts daily.

Speakes denied that Duarte is in trouble, saying, "He's done a courageous and effective job. As far as passing judgment on what is going on down there at the moment, I don't want to specifically comment on that."

The other administration officials said diplomats from other Central American and Caribbean nations have protested that El Salvador has received an unfair share of the aid pie.

Last year, Congress cut drastically, then approved three administration requests for Salvadoran aid, providing a fiscal 1984 total of $329 million in economic aid and $196 million in military aid. With less debate, it then approved $326 million in economic aid and $128 million in military help for fiscal 1985.

The 1985 figure implements the first stage of recommendations from the Special Bipartisan Commission on Central America chaired by former secretary of state Henry A. Kissinger.