The South African Federation of Trade Unions (Saftu) says Workers' Day is an occasion not only to celebrate workers' victories, but also to remember those who died in one of the most horrific accidents in the country's history.

The driver apparently lost his bearings in the dark, took a wrong turn and drove down a gravel road, eventually plunging the bus into the dam at around 05:00.

"A day of celebration became a day of grief as the grim news was passed around all the other May Day rallies around the country," Saftu general secretary, Zwelinzima Vavi, said.

Condolences and expressions of shock and regret poured in from all over the country.

It was later confirmed that the bodies of 51 workers had been recovered. Only ten workers survived after they were rescued by local municipal official Len Slabbert in his inflatable boat.

None of the survivors were seriously injured.

One of the worst accidents in SA's history

ANC Free State leader Ace Magashule said at the time that most of the dead were members of the South African Municipal Workers' Union, two were National Education and Allied Workers' Union members and at least one was a Communication Workers' Union member.

The dam was then renamed the Sol Plaatje Dam.

"These heroes and heroines lost their lives in the course of supporting their fellow workers on Workers' Day. They must never be forgotten," Vavi, who at the time was general secretary of Cosatu, said.

"It would be very wrong not to pause to bow our heads in memory of our comrades who perished in one of the worst road accidents in South Africa's history."

News24