JOHANNESBURG - Former South African president Jacob Zuma has denied corruption allegations against him, saying the charges are part of an international intelligence conspiracy that started more than 25 years ago to assassinate his character.

Zuma is appearing before a state commission that is probing wide-ranging allegations of corruption in government and state-owned companies.

Zuma dismissed the accusations against him saying that they stemmed from efforts by South Africa's previous apartheid regime and other foreign intelligence agencies to have him removed from powerful positions in the African National Congress, now the ruling party.

This, he told the commission, was because these intelligence agencies had infiltrated the ANC and feared that Zuma would either expose their spies.

Zuma's first day on the stand saw him staging a fightback against what he claims that he is corrupt.

He alleged that one of the witnesses who made allegations against him at the commission, former mining minister Ngoako Ramatlhodi, had been recruited by the intelligence agencies as a spy during the apartheid days.

He also questioned the fairness of the state commission, saying it was also part of the alleged conspiracy against him.

Among some of the allegations Zuma faces are that members of the wealthy Indian family, the Guptas, influenced his cabinet appointments when he was president and subsequently swayed the awarding of lucrative state contracts.

In this phenomenon, known here as 'state capture', the Gupta family businesses allegedly took control of a large number of government departments and state-owned enterprises including the struggling power utility, Eskom.

Zuma told the commission that his relationship with the Guptas was nothing unusual or unlawful as they also had relationships with his two predecessors, former presidents Nelson Mandela and Thabo Mbeki.

“They were friends with Mbeki and with Mandela as well, and others. In fact, they were stronger with Mbeki,” said Zuma.

Earlier Monday Zuma was asked about allegations made by a former cabinet spokesman, Themba Maseko, that he had personally called him and tried to influence the award of significant government advertising contracts to the Guptas' now-defunct media businesses.

Zuma denied this, saying he could not remember any such intervention.

Zuma told the commission that he had suggested to the Guptas that they should start a newspaper and a broadcasting channel, which they did establish.

About 300 people gathered outside the commission venue to show their support for Zuma.

Others who came to show their support for the controversial former president included his son, Duduzane, who was last week found not guilty of culpable homicide related to a 2014 car crashed that killed a taxi passenger.

Two former cabinet ministers and two former deputy ministers also attended the commission to show their support for Zuma.

Zuma continues his testimony this week.