South Africa has signed an extradition treaty with the United Arab Emirates (UAE), the Justice Minister Michael Masutha said on Thursday, raising the prospect of the Gupta brothers, friends of former president Jacob Zuma, returning to face corruption charges.

The Indian-born brothers - Ajay, Atul and Rajesh - have been accused of using their ties with Zuma to siphon off billions of rand in State funds and of inappropriately influencing cabinet appointments.

The Guptas are believed to be in Dubai where they own property and businesses and police have issued an arrest warrant for Ajay Gupta over a corruption case.

The Guptas and Zuma, who have repeatedly denied wrongdoing, could not be reached for comment.

Masutha told Reuters that treaties on extradition and legal assistance had been signed with his counterpart Sultan Saeed Al Badi on Tuesday in Abu Dhabi.

"I will not at this stage comment on individual matters," Masutha said when asked about the Guptas.

A long-awaited inquiry into allegations of inappropriately influencing government decisions, known locally as "State capture", opened last month with witnesses testifying that the Gupta brothers tried to bribe or threaten them.

The Guptas left South Africa earlier this year around the time Zuma resigned under pressure from his own party.

Activists, opposition politicians and members of the ruling African National Congress have been calling for an extradition treaty to be agreed with the UAE so the Gupta brothers can be ordered to return to South Africa.

"This means the infamous Guptas are fast running out of places to hide as they can now face extradition to finally answer for state capture," said Natasha Mazzone, Democratic Alliance shadow minister on State companies.