South Korea's military-guided government imposed total martial law today, one of a series of moves that included the arrest of prominent opposition leader Kim Dae Jun, the banning of all political activity and the closing of all universities throughout the country.

The leader of the Democratic Republican Party, Kim Jong Pil, several student leaders and some professors also were arrested in what appeared to be a military drive to throttle dissent and expand control over the country. t

The move ended a period of liberalization that began last October with the assassination of President Park Chung Hee and reached a peak last week with three days of student demonstrations for democratic reforms. The protests were denounced but tolerated by the government.

The government still was being nominally directed today by caretaker President Choi Kyu Hah, but it was clear that the military authorities who had shared power with him were calling most of the shots.

A government spokesman announced at midnight that the entire country had been placed under martial law, a legal change that broadened the military's power. Culture and Information Minister Lee Kyu Hyun said the nation faced an "emergency situation" becuase of troop movements in North Korea and because of civil disturbances that had spread around the nation.

He did not elaborate on the alleged movement off communist forces in North Korea. A similar claim that such movements occurred last week was discounted by American military authorities in Seoul.

The crackdown on civilian politicians was swift. According to one reliable source, Kim Dae Jung was seized in his home near downtown Seoul about 11 o'clock last night when about 60 armed men surrounded his house. Furniture was wrecked, and Kim was taken to an unknown place of detention.

Perhaps South Korea's most well-known opposition leader, Kim Dae Jung is a caustic critic of the Choi government and the nation's military leaders and had planeed to run for president when new elections were called. He had run against Park in 1971 and later spent 33 months in prison for violatin one of the late president's emergency decrees.

Kim Jong Pil, who also had intended to run for president, is head of the Democratic Republican Party that once was Park's political vehicle. His whereabouts were not known this morning. A secretary declined comment except to say he was not at home.

It was believed that Kim Young Sam, head of the opposition New Democratic Party, had not been arrested, but he could not be reached for comment.

In their first proclamation under full martial law, military authorities ordered all universities and schools closed and banned all political gatherings. It was not clear whether that included sessions of the National Assembly, which was scheduled to meet Tuesday to discuss a resolution calling the end of the limited martial law in effect until today.

The proclamation also banned any "slanderous statements" against the present or former chief of state, Choi or Park.

The streets of Seoul were quiet today but Army troops were stationed at every college campus and armored cars and troops were placed around newspaper offices, radio stations and public buildings.

The military proclamation also banned all "fabricated" rumors, and appeared to ban strikes by workers. There have been several hundred labor disputes in South Korea recently.

The military crackdown was a victory for the group of generals led by Lt. Gen. Chon Doo Hwan, who directed a December coup within the military and who has risen steadily in power since. He now directs the military intelligence services and the Korean Central Intelligence Agency.

The country had been under nearly total martial law since Park's assassination, with only one remote province exempted. That province had been omitted for a technical reason that had the effect of limiting the military's power. Today's impositon of total martial law throughout the country gives the military command more power and broad jurisdiction over all civilian activities.

Although the government cited student demonstrations as a reason for imposing total martial law today, the protests actually had ceased in Seoul last Thursday night and were dying out elsewhere.

The crackdown on students began yesterday evening, about six hours before the new proclamation.

Hundreds or armed riot policemen and plainclothesmen swooped down on a meeting of 105 student leaders from 57 universities who had gathered at Ewha Women's University. Many escaped as the police surrounded the campus, but about 25 were seized. Ten were released later, apparently because they were found not to be student leaders.

According to one report, the students had gathered to discuss ways of getting support from the public at large for their antigovernment program.

It was the first time during the spring student protest movement that riot police had entered a campus. Under a compromise reached weeks ago, universities had been granted autonomy indealing with demonstrations as long as they remained on campus.

The students last week had demanded the resignation of Prime Minister Shin Hyon Hwack and the immediate retirement of Chon. That and other student demands had been adopted by both the main opposition leaders, Kim Dae Jung and Kim Young Sam.