The US Treasury announced sanctions against the controversial Gupta family and associate Salim Essa, it said in a statement on Thursday.
“The Gupta family leveraged its political connections to engage in widespread corruption and bribery, capture government contracts, and misappropriate state assets,” said Sigal Mandelker, the Treasury Under Secretary for Terrorism and Financial Intelligence.
The sanctions target Ajay Gupta, Atul Gupta and Rajesh Gupta, as well as their business associate Salim Essa.
The four have in the past denied any wrongdoing.
“The Guptas and Essa have used their influence with prominent politicians and parties to line their pockets with ill-gotten gains,” the US Treasury statement added.
It did not specify the sanctions against the four except to say that the Treasury would “continue to exclude from the U.S. financial system those who profit from corruption”.
The four are accused of unlawfully benefiting from South African government contracts during the rule of former President Jacob Zuma.
Mr Zuma’s successor, Cyril Ramaphosa, took office on a pledge to curb corruption.
The Guptas have fled South Africa, and are said to be living in Dubai.
In February, South African authorities said that Ajay Gupta was no longer wanted by police, and an arrest warrant for him, issued a year earlier for corruption charges, was cancelled.
The authorities had sought to question Mr Gupta on allegations that he attempted to bribe former deputy finance minister Mcebisi Jonas.
Mr Gupta has denied the charges.