Deputy President Kgalema Motlanthe has asked the Public Protector to investigate "bribery" allegations made against his partner in a weekend newspaper report.

Motlanthe had written to Public Protector Thuli Madonsela requesting her to investigate allegations made against him and Gugu Mtshali in the Sunday Times newspaper, his office said in a statement.

"Both Deputy President Motlanthe and Ms Mtshali are firmly of the view that they have committed no wrongdoing of any kind in relation to the alleged events described in the Sunday Times story," his office said.

The report alleged that Mtshali had been implicated in soliciting a R104 million "bribe" to obtain government support for a South African company trying to clinch a R2 billion sanction-busting deal with Iran.

Mtshali, former De Beers executive Raisaka Masebelanga and others allegedly met with representatives of 360 Aviation to solicit the bribe.

This was reportedly in an attempt to secure a R2bn deal to allow a front company to supply United States-made Bell helicopters and spare parts to the National Iranian Oil Company via South Africa, the newspaper reported.

Managing director of 360 Aviation Barry Oberholzer was quoted as saying: "We believe we were being asked for a bribe... in exchange for government support."

Motlanthe said he was unaware Mtshali had any connection to the company.

Motlanthe's spokesman Thabo Masebe said: "He has at no stage discussed such a matter with any person, including the department of trade and industry."

Mtshali told the newspaper she had never attended a "formal meeting" with 360 Aviation.

However, the Sunday Times claimed to have an audio recording of the meeting, on which Mtshali's voice was allegedly heard. The alleged deal reportedly failed because 360 Aviation could not reach an agreement with the National Iranian Oil Company.

The US, which manufactures Bell helicopters, prohibits the sale of military equipment to Iran.

Motlanthe's office said the allegations were serious and needed investigation.

"Having regard to the serious nature of the allegations and imputations of the story, Deputy President Motlanthe is of the view that the issues should be subject to an investigation by the Public Protector," his office said.

"The deputy president and Ms Mtshali will make themselves available to provide any information to the Public Protector should she decide to investigate the allegations."