S Africa home affairs minister lied under oath: watchdog

South Africa's public standards watchdog said Tuesday that the home affairs minister had violated the constitution when he lied under oath in court, triggering immediate calls for him to resign.

Malusi Gigaba, 47, was investigated by the public protector ombudswoman after testifying last year in a court case filed by a company controlled by the wealthy Oppenheimer family.

Public protector Busisiwe Mkhwebane in her report recommended that President Cyril Ramaphosa take disciplinary action against the minister for "telling an untruth under oath and before a court of law".

The allegations were probed after a complaint from the opposition Democratic Alliance (DA) party.

"The DA has repeatedly called for constitutional delinquent Gigaba to be sacked, yet inexplicably he has remained a fixture in the cabinets of both Jacob Zuma and Cyril Ramaphosa," the party said in a statement.

The court case hinged on whether Gigaba had given the Oppenheimers' approval to have a private terminal at Johannesburg airport.

Gigaba at the weekend has said he was the target of extortion attempts after a private sex video was stolen by hacking.

He served as finance minister for a year under Jacob Zuma, who was ousted as president in February over mounting graft scandals.