SEOUL, South Korea (AP) _ Students chanting ''Yankee go home 3/8'' fought police with firebombs and rocks today after authorities banned a march to the North Korean border, and striking workers rioted in two southern cities.

Several thousand radical students clashed with riot police on at least five campuses in Seoul after the government banned a march to Panmunjom border truce site 30 miles north of Seoul for talks with communist students.

Twenty student delegates were seized by police as they tried to get to the border to meet the North Korean student delegates to discuss taking part in a youth festival in Pyongyang in July and other ways to reunite the two nations.

About 6,000 striking workers clashed with riot police in the southeastern industrial cities of Masan and Changwon, police said. Strikers in Changwon poured oil on some streets and set them ablaze and protesters in Masan pelted police with bits of scrap metal.

It was the fifth day of clashes in Changwon.

Riot police blocked 4,000 students trying to march out of Seoul National University. Screaming students armed with metal and wood clubs attacked riot police with firebombs before troopers stormed onto the campus firing tear gas.

Black police vans armed with multiple tear gas launchers fired hundreds of the bombs as fighting flared around the sprawling campus. It was surrounded by 3,000 riot police in green combat fatigues and visored helmets.

Police officials said people were hurt, but they had no figures.

Students clashed with riot police on at least four other Seoul campuses. About 700 students battled troopers with firebombs and rocks for two hours at Yonsei University.

Student clashes also erupted in the southern port of Pusan and radicals seized a government prosecutors' office in Taegu, according to Yonhap, the South Korean news agency.

Student leaders lashed out at South Korean President Roh Tae-woo and the United States in rallies before the clashes, accusing them of perpetuating the division of the Korean peninsula. Speakers called for immediate unification with the communist north.

''Overthrow Roh Tae-woo, who blocked our vital march to the north for talks with North Korean students. Let's raise a flag of anti-facism and anti- Americanism and march to Pyongyang,'' a leader said at Seoul National University.

The government banned the march to Panmunjom on grounds it posed a threat to public safety and the government alone has authority to deal with the rival north.

Dissident leaders have said they will go ahead with planned anti-government protests this weekend, including plans for a major labor rally in Seoul on Sunday to mark the international May Day labor holiday. The government has banned all the demonstrations.

The radical students and allied dissident groups lack popular support because of their extremism and are not seen as a threat to the Roh government.

But government leaders are concerned about growing labor unrest and a wave of increasingly violent strikes for better pay and improved working conditions. Top opposition leaders Wednesday appealed to radical students and workers to halt protests and warned continued unrest could undermine democratic development in South Korea.

Also today, 3,400 police officers offered their resignations to protest an alleged assault on a police superintendent by an opposition lawmaker.

National Police Director Jo Chong-suk said he ordered all the resignations returned, and government officials said his action would defuse the situation.

It arose after legislator Sim Wan-koo reportedly slapped Superintendent Chung Moon-young in the face during a labor protest Thursday in Changwon.

Dissident leaders claim Roh is a front for military rule. Roh won elections in December 1987 after rival opposition candidates split the opposition vote.