“We are deeply saddened by this tragic loss of life and livelihoods. The thoughts of the people of South Africa are with the families and friends of the victims of this tragic accident,” Zuma said in a statement.
“We wish those injured in the accident a speedy recovery.”
At least 57 people died when an overloaded passenger train sped off the rails in the Democratic Republic of Congo.
The government warned that the figure was likely to rise as rescuers struggled to reach the remote area.
The train was travelling north from the town of Kamina in the southern province of Katanga to Mwene-Ditu in the diamond-mining province of Kasai-Oriental, the Agence France Presse (AFP) reported.