The South Korean government is reported to have placed at least 63 dissidents under house arrest in preparation for President Carter's state visit starting on Friday.

Several of the prominent religious and political leaders affected said in telephone interviews that they believe the government is restricting them to stifle dissent during the visit. One said his police guard acknowledged Carter's impending arrival as the reason for the restriction.

Those kept under guard at their homes include a former president, several prominent clergymen, opposition leader Kim Dae Jung, and at least two officials of the Korean Council of Churches.

According to the Council of Churches, 63 persons have been placed under house arrest within the past 10 days. The council's secretary general, the Rev. Kim Kwan Suk, said two of his aides were restricted to their homes and told it was for the duration of Carter's visit.

The government acknowledged that some persons have been placed under "restricted residence" but denied that it has anything to do with Carter's visit.

South Korea has always been a severe test of Carter's international human rights policy and some dissidents have protested that his visit this weekend constitutes an embrace of what they term a repressive regime. By the Council of Churches' calculation, 340 South Koreans already were being held as "political prisoners" for having violated a proclamation that prohibits any public criticism of the government.

How Carter will handle the issue is a touchy question for the White House and for President Park Chung Hee's government. A South Korean government official said today he expects Carter to make only a general statement of human rights policy and not to direct critical remarks at the Park government.

The U.S. embassy issued this statement on the house arrest: "We, too, have had information about some detentions and we have made it clear to the Republic of Korea government that we do not approve of any actions in connection with President Carter's visit which go beyond normal security precautions for a visiting head of state."

Carter is to meet Sunday with about a dozen religious leaders, some of them angry that their colleagues are being kept under guard because of his visit.

"It's getting worse," said the Rev. Kim. "There are so many people under house arrest because of his coming. That is the irony of Mr. Carter's visit. It's disgraceful. Just because of his visit the Korean government has to suppress its own people."

Kim listed several Seoul ministers restricted to their homes. "They are very angry, not just at Park but at Mr. Carter as well."

Former president Yun Po Sun said he was placed under house arrest last Saturday after he participated in a demonstration and that he does not know how long it will last.

He and his wife, who was not in the demonstration, are prevented by guards from leaving the grounds of their home and are allowed visits only by news reporters and by members of the National Assembly. He said he thinks that Carter's visit is the reason but he has not been directly told so.

Kim Dae Jung, the former opposition leader recently released from a prison term imposed for violating the antidissent proclamation, said he has been under house arrest for a month under the same restrictions as former president Yun.

He said he did not know the reason. Many of my friends and I suspect that it is because of Carter's visit," he said.

Asked about Kim Dae Jung's case, a government official said "We do not call it house arrest but we want to be sure that he doesn't cause any trouble. We call it restricted residence. He can go out to funerals and marriages. But to attend political rallies - hell, no"

Another government official asserted that "some" of those restricted are violating terms of suspended sentences. He said the restrictions have "nothing to do with Mr. Carter's visit and they have nothing to do with politics. At this time, some of the people whose sentences have been suspended are trying to violate the law. Therefore, some of them are under restrictive residence according to the pertinent laws and regulations of our country. But the number is very small."

However, Lee Moon Yong, a former professor at Korea University, said he has been told each day since Sunday by his police guard that his house arrest is because of Carter's visit. He has been restricted to his home since June 7 and other reasons were given prior to Sunday.

Lee said he telephoned the U.S. Embassy to protest and was told to dictate a complaint to a Korean interpreter. He never received any reply but learned from friends that his complaint had been given to the embassy's human rights official John Lamazza, he said.