At least 12 supporters of South Africa's Economic Freedom Fighters (EFF) party have died, and 32 others were injured in a bus crash, EFF says on Tuesday.

According to EFF spokesperson Sinawo Thambo, the accident occurred near the town of Vryheid just after midnight as the group was returning to Pretoria from a Youth Day rally in Durban on Monday.

A preliminary report from the Road Traffic Inspectorate (RTI) says the bus was struck on its side by an oncoming truck, ripping it open, state media outlet SABC reports.

KwaZulu-Natal Provincial Transport and Human Settlements MEC Siboniso Duma told journalists he received a report shortly after midnight indicating 10 fatalities. The death toll then rose to 12 by 5 am on Tuesday morning.

Duma said both truck and bus drivers survived the crash and were transported to the hospital.

In February at least nine members of the African National Congress (ANC) died in a bus crash on their way home from the party’s manifesto at the Moses Mabhida Stadium in Durban.