Mpumalanga Premier David Mabuza hitched a lift with the Guptas in their private jet from Moscow to Johannesburg after being treated for poisoning in Russia.
The Times has been told that President Jacob Zuma's son, Duduzane, offered him the lift on the Gupta Bombadier Global jet in November last year.
This was confirmed by Mabuza's spokesman, Zibonele Mncwango.
"We can confirm that the premier travelled to Moscow to seek medical treatment for poisoning.
"The premier was gravely ill and was not in a position to easily walk or carry himself onto a national airline, hence he accepted the offer from Duduzane, which could have possibly been lifesaving."
Mabuza's presence on a Gupta flight with Duduzane was first revealed last week in court papers served on Home Affairs Minister Malusi Gigaba by the Oppenheimer family's aviation company, Fireblade.
The papers detail how two former Gupta pilots claimed that the Saxonwold family allegedly tried to wrest control of Fireblade's private terminal at Johannesburg's OR Tambo International Airport from the Oppenheimer family.
The Oppenheimers are taking Gigaba to court to force him to declare their terminal an international entry point.
The company says that both Gigaba and state arms maker Denel, from which it leases the land on which the terminal is built, have flip-flopped several times under pressure from the Guptas in the granting of permission for it to offer international customs and immigration services at its terminal.
Fireblade director Robbie Irons said in an affidavit that a former Gupta pilot had relayed a message to him from Tony [Ajay] Gupta that Fireblade would get the approval only if it found a BEE partner linked to the Guptas. The conversation took place on the flight Mabuza was on.
Denel and the department have denied that any pressure was exerted by the Guptas.
The department said the case was a dispute between Fireblade and its landlord and it could not get involved.
The Guptas said: "These allegations will not go unchallenged. It has become custom to accuse the Gupta family of wrongdoing when one was unsuccessful in any venture."