Deputy president Cyril Ramaphosa has called on the Hawks to investigate claims of state capture, eNCA reported.
Ramaphosa reportedly addressed a Cosatu rally in Seshego, Limpopo, on Sunday.
"The president will appoint a commission of inquiry but in the meantime the Hawks must investigate the emails," he reportedly said.
"Corruption is like a snake and before it eats and kills people inside the house, we are saying we want to get rid of corruption. Those who are involved in corruption we are saying: Your days are numbered. We are coming after you ..."
According to News24, Ramaphosa said that MPs in Parliament also had concerns that investigations should be conducted into state capture.
"The parliamentarians are saying investigations must be conducted while the country is waiting for the president to appoint a commission of inquiry," said Ramaphosa.
Cosatu reportedly announced at the rally that it would be participating in a mass strike soon to protest against state capture. The trade union federation has publicly asked Zuma to step down and has backed Ramaphosa to lead the ANC after its December elective conference.
On Sunday, Ramaphosa urged delegates to the conference not to be swayed by money.
"You must only be influenced by one thing, the interests of the ANC. You must not allow money to influence you. You must be guided by the values and the principles of the ANC," he said.
"We must stop the division among us, we must stop factionalism, we must embrace unity, we must embrace working together, because if we are divided, we will not be able to win in 2019. IIt is only when we are united that we will be able to succeed in 2019."