Swaziland's main underground opposition party has warned that this will be a month of mass action against the government of King Mswati III.
Renewed unrest over lack of democracy stems from anger at the eviction of two traditional leaders, who have sought asylum in South Africa.
Chiefs Mliba Fakude and Mtfuso Dlamini III and their followers were evicted from their land for opposing the imposition of the king's older brother as their local chief.
Protesters claimed that scores of families had been displaced and more than 70 children made refugees. The police have reportedly injured at least 14 students and teachers, one student seriously. The University of Swaziland and schools have been closed.
In the capital, Mbabane, and in the town of Manzini, thousands of students, teachers and workers protested against the evictions. Outside the king's palace, police used teargas and batons to halt a demonstration by 300 students and teachers organised by the Swaziland National Association of Teachers to call for the restoration of the chiefs. In Mbabane, police used teargas against 150 or so protesting members of the Swaziland Federation of Trade Unions.
David Simon, professor of geography at Royal Holloway, London University, said: "The flight of the chiefs gives this domestic political dispute and land conflict an international dimension. If instability is seen to reach a critical level, intervention by forces of the Southern African Development Community (which is in effect led by South Africa) - as happened in Lesotho - cannot be ruled out, although the Lesotho experience was ill-planned and counterproductive."
Professor Simon said the king is losing his modernising image. "Swaziland remains very authoritarian and traditional. The evictions reflect the king's autocratic power and the inability of even senior chiefs to challenge his writ. A significant element of Swazi society would like to replace what they see as an anachronistic monarchy with a democracy. These events could play into their hands."
A highly restrictive new industrial relations act has cost Swaziland trade concessions with the United States. Swazis fear this will damage the economy.