Former deputy minister of finance Mcebisi Jonas still has a vital role to play in South Africa, the Democratic Alliance's (DA's) David Maynier said on Thursday.
Jonas was fired from the finance ministry along with Minister Pravin Gordhan on Friday, and he later resigned from Parliament.
His resignation was confirmed on Thursday.
Maynier was referring to Jonas' allegations against the controversial Gupta family, whom he said had offered him millions to take the finance minister job, which he had refused.
"Now nothing stands in the way of the former deputy minister co-operating with the investigation being carried out by the Hawks. He could be the star witness in what could amount to aiming a 'political headshot' at President Jacob Zuma," Maynier said.
"We can only hope the former deputy minister will have the courage and energy to fight on against 'state capture' in South Africa."
Former public protector Thuli Madonsela interviewed Jonas after he said the Gupta family offered him Nhlanhla Nene's job as finance minister.
He told Madonsela the family offered him R600 000 in cash during a meeting at their Saxonwold, Johannesburg, residence.