Defiance of South Korea's new military rule grew into a provincial rebellion today as citizens in the city of Kwangju battled with police and troops, and demonstrations spread to three other towns.

At least 11 deaths were reported in Kwangju last night and today. Other accounts indicated there had been at least 25 fatalities since the weekend. Citizens seized guns and ammunition from Army storerooms and crashed into police blockades with commandeered military vehicles, buses and taxicabs.

More than 100,000 citizens, including students from two universities, reportedly poured into the streets to battle riot police and troops. Demonstrations spread to the town of Naju, Changsung and Mokpo, all in South Cholla Province.

In Seoul, the martial law command blamed the insurrection in part on North Korean "spies," whom it accused of starting fires, destroying buildings and inciting local antagonisms.

The fierce fighting in Kwangju began four days ago as a student protest against the military takeover Saturday night, which was followed by arrests of key political figures and scores of other dissidents.

With the rest of the country quiet and a group of generals holding power here, a new acting premier was announced. He is Park Choong Hoon, 61, a retired Air Force general, former minister for economic planning and currently head of a trading association.

A Cabinet announced to replace the one that resigned yesterday included eight key carryovers and 11 new ministers.

The new Cabinet represents the choices of military leaders who engineered the bloodless coup Saturday, when the former ministers signed a piece of paper authorizing total martial law.

With generals ruling the country from behind the scenes, the choice of the premier was not formally announced by President Choi Kyu Hah, who has not been seen in public since Friday. Instead, a presidential spokesman telephoned the name to newspaper offices.

Korean reporters assigned to cover the presidential office at present are not permitted to go near it.

Park carries the title of acting prime minister because the appointment of a permanent one would require approval of the National Assembly, which the martial law command has barred from meeting.

Presidential spokesman Suh Ki Won said the "basic direction" of the Cabinet would be to ease public worries, particularly about economic problems.

Park was an Air Force officer from 1953 to 1961, retiring as a two-star general. He served for two years under the late president Park Chung Hee as deputy prime minister for economic planning. Since 1973, he has been president of the Korean Trade Association, which represents most of the country's large trading companies. Never prominent in politics, he is, however, well known in business circles.

Meanwhile, the military leadership said it has arrested prominent opposition leader Kim Dae Jung on grounds that he was planning an uprising in an attempt to overthrow the government.

Kim, a former presidential candidate, was seized Saturday at his home in the first round of arrests of prominent politicians and dissidents.

A document circulated by the martial law command, seeking to justify the military takeover, asserted that Kim had controlled recent student disturbances from behind the scenes, hoping to take power by a violent overthrow of the government.

Reports from the fighting in Kwangju were fragmentary most of the day because communications were cut and an attempt was made to prevent anyone from entering the city.

One report said 11 persons were killed, including four police crushed when demonstrators smashed into a blockade with a commandeered bus. Two soldiers and five civilians also were slain, by this account.

At one point, citizens placed the bodies of dead friends on carts and wheeled them through the city square to incite more demonstrations, the reports said.

Two television stations were burned by demonstrators, apparently because they followed orders to broadcast government statements. The martial law command said 21 police stations were destroyed or damaged.

The fighting began Sunday when students from two local universities demonstrated against the military takeover and demanded an end to martial law. Paratroopers reportedly clubbed them with rifle butts and ripped the clothes off some. The protest has spread sporadically, as thousands of citizens joined in.

Kwangju, with a population of perhaps 700,000, is the capital of South Cholla Province -- which has a record of rebelliousness toward the central government and which is the birthplace of Kim Dae Jung. It is an agricultural area left behind by South Korea's industrialization and considered to have high unemployment.

Military reenforcements have been rushed in but for four days have been unable to quell the uprising. Citizens have demanded that the troops be removed and that all prisoners be released. The provincial governor was reported to be supporting their demands.

In a broadcast tonight, the martial law commander, Lt. Gen. Lee Hui Sung, said the protest had grown to proportions of a "grave situation" because of the agitation of North Korean "spies" who infiltrated the city.