The South African trade union confederation COSATU plans to force a blockade of Oshoek and Matsamo border posts with Swaziland in solidarity with pro-democracy activities in the kingdom.
It is to support the Global Week of Action for Democracy in Swaziland and will take place on 6 September.
It has also announced support for a picket at the Swazi Consulate in Johannesburg on the same day.
In a statement COSATU said Swazi people had rejected the so-called tinkhundla elections currently taking place in Swaziland as undemocratic and a 'royal circus'. It said the elections were, 'managed by an incompetent, discredited and sycophantic bunch of [King] Mswati's puppets called the Elections and Boundaries Commission (EBC).'
King Mwsati rules Swaziland as sub-Saharan Africa's last absolute monarch. All political parties are banned from the election and the parliament is widely seen outside of Swaziland as powerless.
Separately, a march is planned in the Swaziland capital Mbabane, jointly organised by the Swaziland National Union of Students, the Swaziland United Democratic Front (SUDF) and the Swaziland Democracy Campaign (SDC), on 5 September 2013.
In a statement, organisers predicted 10,000 people would take part in the march.
On 6 September, the SUDF and the SDC also plan to run what is billed as a 'people's summit' in Manzini with the intention 'to profile the boycott of the Tinkhundla election and provide an alternative'.