The Indian brothers who are accused of corrupting South African President Jacob Zuma lashed out Friday at "xenophobic and hate speech" against them, and denied benefiting from links to the government.

The Gupta family's power has allegedly extended to appointing ministers under Zuma, whose presidency has been engulfed in graft scandals and growing disillusion over the country's post-apartheid prospects.

"As the global economic slowdown began to bite, the family became the scapegoat for every calamity and misfortune that South Africa has faced," the Guptas, who moved to the country in the 1990s, said in a statement.

"We have been quiet until now but given the recent xenophobic and hate speech against us, now is the time to set the record straight."

The statement was printed across a double-page spread in The New Age -- the pro-government paper they own -- under the headline "Gupta family: The Inconvenient Truth".

"It is absurd to suggest that we benefit from government business when only less than one percent of the (family's) business is with the South African government," it said.

The three Gupta brothers said they employ 5,000 staff in mining, engineering, technology, media and property businesses built up from a small marketing company based in a Johannesburg garage.

The statement came after deputy finance minister Mcebisi Jonas said that they offered him the top job in the treasury last year.

Jonas said he rejected the offer, but several other ministerial appointments have been widely reported as being due to the Guptas.

The ruling African National Congress (ANC), which led the struggle to end apartheid, began a three-day meeting of its national executive committee (NEC) on Friday near Pretoria.

"We will focus on two major areas... the economy, growth in particular, and local government elections," ANC secretary general Gwede Mantashe told reporters, adding the Gupta allegations were not on the official agenda.

Zuma retains a strong hold over the party, which easily won elections in 2014.

But opposition parties are hoping to make gains in the local polls this year as anger grows over lack of racial transformation in two decades since the end of white rule, soaring unemployment and high inflation.

Some ANC stalwarts have called for Zuma, 73, to retire before his term ends in 2019.

"If he stands down, we have a chance of recovering the situation. If he does not, we are going to take such a beating in the local elections," Denis Goldberg, who served 22 years in prison under apartheid, told AFP.

"When I see... business people apparently taking over some of the state functions, I am appalled."