SA trade unions and political parties called on South Africans on Tuesday to show support for an anti-government march in the tiny mountain kingdom of Swaziland.

The African National Congress Youth League said it supported the "youth of Swaziland to fearlessly confront the Swaziland monarchy and fight until it has been brought down to its knees on the uprising that starts on Tuesday".

"The youth of Swaziland should be like the youth of South Africa in 1976 who stood fearlessly against the armed apartheid regime and sustained militant protests and struggles until the regime came to the table for negotiations which brought political freedom and democracy," the ANCYL said in a statement.

"The youth of Swaziland should be inspired by the youth of Tunisia and Egypt, who brought down regimes sympathetic to imperialists."

The Communication Workers Union (CWU) said it was time for the people of Swaziland to be "brave".

"CWU encourages all South Africans and international countries to join the Swaziland Solidarity Network (SSN) and support the people of Swaziland to demolish the corrupt regime that's looting from the poor working people," the CWU said in a statement.

The Young Communist League of SA, the SA Communist Party (SACP) and the Congress of SA Trade Unions (Cosatu) called on their members to protest outside the Swaziland embassy in Pretoria in support of the "April 12 Swazi uprising" against King Mswati III.

It was responding to a call from the SSN for South Africans to support the protest march planned in Africa's last absolute monarch on Tuesday.

"The demonstration is in support of popular mobilisation by the people of Swaziland for the regime of King Mswati to relinquish its authoritarian position of power and give way to legitimate aspirations of the people to a democratic Swaziland," said SSN spokesman Lucky Lukhele in a statement.

Swazi foreign minister Lutfo Dlamini told SABC radio on Tuesday morning that the Swazi government had been "engaging" with those opposed to the monarchy.

"We are at a stage where we need to find a lasting solution," said Dlamini.

The SSN said on Monday that five activists had been arrested ahead of planned protests in Swaziland from Tuesday.

Agence France-Presse (AFP) reported that Prime Minister Barnabas Dlamini last week declared the demonstrations illegal.

Last month, trade unions protested against cuts in civil servant salaries while the king and his 13 wives live in luxury.