Kim Dae Jung, the imprisoned South Korean political leader, was transferred from his cell to a hospital early today but he remains a prisoner, government officials said in Seoul.

A Justice Ministry spokesman said Kim is suffering from an arthritic knee and that a doctor decided he needed attention by a specialist.

The circumstances of his transfer, however, raised new questions about the condition of the prominent political leader, who was imprisoned for violating a degree that prohibits criticism of the government.

According to the Kyodo News Service, which quoted reliable sources in Scoul, Kim was removed from the remote Chinju Prison at 3:40 a.m. He arrived at Seoul National University Hospital 10 hours later.

One government official said movement of a prisoner at that time was not unusual. He cited security reasons and the light automobile traffic as the reasons Kim was driven to Seoul in the early morning.

Although the government described his ailment as arthritis, his friends said that Kim's general physical condition has been growing worse in recent weeks.

"He has been very weak lately and he needs treatment," said the Rev. Kim Kwan Suk, secretary general of the South Korean Nation Council of Churches. "He becomes very weak in the cold weather."

Kim opposed President park Chung Hee in the election of 1970 and thereafter became a strong critic of the park government, contending that it was stifling political opposition and restricting human rights.

He and 17 others were arrested in March 1976 for issuing a declaration criticizing Park's government and Kim has been in prison ever since. He was sentenced to five years at hard labor.

With the South Korean government under U.S. pressure to change its repressive policies against political dissidents, there has been speculation recently that Kim might be released.

Kim is one of about 200 political prisoners in South Korea. Two small groups were released last summer and a committee of dissidents has been negotiating with the South Korean Central Intelligence Agency for the release of more.

The government has refused to release them, however, unless they sign a statement confessing they broke the law and offering to repent. According to Kim's friends and relatives, he has refused to sign the statement.

South Korean authorities said today they did not know how long Kim would remain in the hospital and there was no information on whether he would be returned to the Chinji prison when his treatment is finished. His wife lives in Seoul in a small home constantly watched by the KCIA.