South Africa's deputy finance minister has confirmed reports alleging that he was offered the position of finance minister by a member of the wealthy and controversial Gupta family.
Mcebisi Jonas says he rejected the offer, calling it "a mockery of our hard-earned democracy".
The opposition has long accused President Jacob Zuma of letting the Guptas wield excessive influence.
The Indian-born family has built up holdings in mining, travel and media.
The Guptas, who arrived in South Africa in 1993, also have huge interests in computers, air travel, energy, and technology.
They said Mr Jonas' statement was political point-scoring.
In 2013, there was an outcry after a private jet carrying guests to the wedding of a Gupta family member was allowed to land at a South African military air force base in Pretoria.
The opposition has said that links between President Zuma and the Guptas were so close that they have been nicknamed the "Zuptas".
Analysis: Milton Nkosi, BBC News, Johannesburg
The allegations, confirmed by a serving minister, may well represent the lowest point of Mr Zuma's presidency, which has already been beset by multiple corruption scandals.
South Africans have reacted with shock and dismay. Some are already calling for the president to resign.
It is very difficult to see how President Zuma can come out of this latest scandal unscathed.
The ANC's national executive committee's meeting this weekend will face a tough decision: should it keep President Zuma as head of state?
Mr Jonas' shock statement follows questions about the role of the Gupta family in parliament.
He said that "no-one apart from the president of the Republic appoints ministers.
"The narrative that has grown around the issue of 'state capture' should be of concern to all responsible and caring South Africans."
Mr Jonas said he was offered the job of finance minister in December 2015 just before Nhlanhla Nene was sacked by President Zuma.
Mr Zuma then appointed the little-known David van Rooyen, leading to a run on the currency and national protests.
Just days later, Mr Zuma made an about-turn and replaced Mr Van Rooyen with the widely respected Pravin Gordhan.