The South Korean government yesterday displayed the first sign of flexibility about opposition leader Kim Dae Jung's plan to return home, disavowing an earlier official statement that Kim will be imprisoned when he does so.

The unusual disavowal came in a South Korean Embassy statement here amid new indications that the Kim case is complicating plans for South Korean President Chun Doo Hwan to visit President Reagan.

U.S. sources said that a Chun visit to Washington was to have been announced by the two governments today, U.S. time, but that an announcement has been deferred due to the Kim case.

The sources said there is no change now in the plan for Chun to come here, probably in early April. However, deferral of a public announcement, not expected until after Kim's return, indicated a wait-and-see attitude on the part of the White House.

Kim, who has been living in this area since being released from prison and exiled to the United States a little over two years ago, has announced plans to return to his homeland Feb. 8. On Tuesday, in the most authoritative and blunt statement of the Seoul government's attitude, senior presidential aide Choi Chong Yoon told a New York Times reporter in an interview that Kim will be imprisoned as a "revolutionary" when he returns.

State Department officials said Wednesday that the Seoul government's plans to jail Kim could cast a pall over Chun's planned visit. The Korean government was informed through diplomatic channels that public announcement of the Chun visit was being deferred.

Yesterday morning, the Korean Embassy here issued a public statement saying that comments to The New York Times by Choi "were strictly his personal views and do not relate to the position of the Korean government in any manner."

Those acquainted with Choi, secretary for political affairs of the Korean presidency and a former military officer, doubt that he would say anything in an on-the-record interview with an American reporter without full authorization. Thus, the embassy statement is being taken as a diplomatic way of easing the confrontation with Kim and the U.S. government.

Late yesterday, a State Department spokesman said, "We welcome the statement that Choi was speaking only his personal views."

An embassy official said his government does not believe that a meeting between Reagan and Chun would be affected by Kim's situation.

Neither Korean nor U.S. officials would comment formally about the failure to announce the Chun visit as had been planned, but there was no denial that the silence was due to developments regarding Kim.