Jacob Zuma was sworn in as president in May
South Africa's government has backed a bid by apartheid victims to sue firms in the US - reversing the position of the previous administration.
A group of South Africans is taking legal action against the companies in a court in New York's southern district.
Daimler, Fujitsu, General Motors, IBM and Rheinmetall are accused of aiding and abetting South Africa's former apartheid regime.
In April, a US court dismissed similar claims made against UBS and Barclays.
The plaintiffs have welcomed President Jacob Zuma's support for their case.
Among other things, they claim that the companies produced parts for vehicles which were used to carry out the assassinations of liberation movement activists and unprovoked shootings of black people during the apartheid years.
"I was tortured and sentenced to five years on Robben Island. I have shrapnel and a bullet in my skull," said one complainant Mpho Masemola, the Sowetan newspaper reports.
Mr Masemola was one of thousands in the country who were arrested under the notorious Section 29 of the Internal Security Act which gave the white-minority government and its police force the power to detain anti-apartheid political activists in solitary confinement for years.
"Those companies must pay for the years of my interrupted education. Had I not been arrested I would be a doctor by now," he says.
The BBC's Mpho Lakaje in Johannesburg says the 26 complainants in the case are hoping to get up to $400bn from the companies.
Justice Minister Jeff Radebe has written a letter to the US District Court announcing that Mr Zuma's government supports the class action brought by Khulumani Support Group against the conglomerates.
This is in stark contrast to the policy of former President Thabo Mbeki who had opposed the lawsuit saying it might put off foreign investors.
The case was lodged in 2002.
Mr Mbeki's government even applied to be a friend of the court in 2006 on the side of the US companies.
"This represents a very significant shift from the government's 2003 position that (it) is not and will not be party to litigation' against companies that did business with and in South Africa during the apartheid period," said Khulumani Group, Sapa news agency reports.
Last year, the US Supreme Court ruled that the lawsuit could go ahead.
Mr Zuma was sworn in in May after winning a bitter power-struggle against Mr Mbeki.
Mr Zuma's supporters hope he will do more to tackle poverty in South Africa - they accused Mr Mbeki of being too close to business interests.