President Carter yesterday fired Maj. Gen. John K. Singlaub as U.S. chief of staff in South Korea for telling The Washington Post last week that Carter's plan to withdraw U.S. troops from Korea is a mistake that will lead to war.

Defense Secretary Harold Brown announced Singlaub's dismissal as chief of staff less than an hour after Singlaub, in uniform, met for 30 minutes with the President. Carter was described Thursday as distressed and angered by Singlaub's remarks.

Brown accompanied Singlaub to the meeting. In a statement issued from the Pentagon afterward, Brown said, "Public statements by Gen. Singlaub inconsistent with announced national security policy have made it very difficult for him to carry out the duties of his present assignment in Korea.

"I have, therefore, recommended to the President that Gen. Singlaub e reassigned, and with the President's concurrence I have directed the secretary of the Army to take action to that effect."

It was the first such disciplining of an American general since President Truman recalled and fired Gen. Douglas MacArthur from command of U.S. and U.N. forces in Korea in April, 1951.

Singlaub's new assignment was not announced. He will retain his two-starrank.

Singlaub, a much decorated war hero with 33 years in the Army, said through an Army spokesman that he "accepts" the decision of reassignment" and is "looking forward" to whatever his new job may be.

"In order to put this matter to rest, Gen. Singlaub has decided not to give interviews or make any comments," the spokesman said, adding that plans are for Singlaub to testify Wednesday before the Investigations Subcommittee of the House Armed Services Committee.

Brown met with Singlaub for almost an hour just before noon yesterday. Then the two drove to the White House to meet with the president, using a side door to avoid reporters.

When Singlaub emerged, he strode quickly to the Defense Secretary's car. His only response to questions was, "I have no comment."

"He's tired, but I think he understands and accepts the decision of reassignment," said Maj. Gen. Gordon Hill, the Army's chief of public affairs, moments after talking with Singlaub.

"Plans are he will go back to Korea to wind up his affairs and get his wife and whether his belongings are, and by that time he should have his reassignemnt orders and he'll proceed from there."

Presumably, Hill said, Singlaub will return to Korea shortly after testify- ing before the Armed Forces subcommittee. The reassignment orders may be issued "early next week," Hill said.

The views that got Singlaub in trouble were given to Washington Post Tokyo bureau chief John Saar in an interview published Thursday. Singlaub said that he and many other senior military officers challenge the wisdom of Carter's plan to remove U.S. troops from South Korea in a phased withdrawal over four or five years.

Carter first announced that would be his policy during the presidental campaign, and he has repeated it since he took office.

"If we withdraw our ground forces on the schedule suggested, it will lead to war," Singlaub said. He predicted that withdrawal of the war-ready 2d Infantry Division in that time frame would seriously weaken defense in the south and encourage North Korean President Kim II-sung to attack.

Within hours after Carter read the account of Singlaub's views, he telephoned Brown and issued the order for Singlaub's return.

The usual situation of a general openly challenging the President's declared policy came on the eye of talks with South Korea to implement that policy.

Carter's only other publicly scheduled meeting yesterday was a morning session with Brown, Joint Chiefs of Staff Chairman Gen. George S. Brown, Under Secretary of State Philip C. Habib and others to give final instructions to Habib and Gen. Brown. They will go to South Korea Tuesday for the talks, described by the White House as "serious consultations with the Republic of Korea."

One White House official said Thursday that Carter was not only angered at having his military policy publicly questioned by a subordinate, but feared Singlaub's remarks would encourage North Korea to consider another invasion of South Korea.