The US Treasury announced sanctions Thursday on South Africa's Gupta family and associate Salim Essa, calling them a "significant corruption network" that dispersed bribes and misappropriated millions in state funds.
The wealthy, Indian-born Guptas are at the centre of a judicial inquiry into rampant corruption during the nine-year administration of South Africa's former president Jacob Zuma.
"The Gupta family leveraged its political connections to engage in widespread corruption and bribery, capture government contracts, and misappropriate state assets," said Sigal Mandelker, Treasury under secretary for terrorism and financial intelligence.
"Treasury's designation targets the Guptas' pay-to-play political patronage, which was orchestrated at the expense of the South African people," she said.
The sanctions immediately freeze any assets the blacklisted individuals have under US jurisdiction and forbid Americans and US businesses -- particularly international banks with any US operations -- from transactions with them.
The sanctions were placed under the US Global Magnitsky Act which targets large-scale corruption and human rights violation.
"Today's sanctions announcement demonstrates the US government's unwavering commitment to supporting the rule of law and accountability in South Africa," the Treasury said.
"We support the anti-corruption efforts of South Africa's independent judiciary, law enforcement agencies, and the ongoing judicial commissions of inquiry."
In that inquiry, the Gupta brothers -- Ajay, Atul and Rajesh -- are accused of fraudulently profiting from government contracts including energy and transport deals through their close association with Zuma.
The investigation has also cast a shadow over President Cyril Ramaphosa, who has denied business dealings with the brothers.