African National Congress (ANC) secretary-general Fikile Mbalula has called former Eskom CEO André de Ruyter a "naysayer" and "right wing", saying he had failed to meet his mandate of turning around the power utility and had instead ventured into the political arena.

Mbalula was responding to allegations made by De Ruyter in a television interview with e.tv on Tuesday.

The former Eskom CEO alleged that there were efforts to cover up corruption at Eskom, despite his attempts to report the matters to government ministers.

De Ruyter also said a particular minister had been involved in questionable activity at Eskom, but he did not name the minister or provide details of the corruption he was referring to.

His interview has angered the ANC.

Public Enterprises Minister Pravin Gordhan immediately demanded that he be investigated, while Eskom's board ended its relationship with De Ruyter on Wednesday.

Eskom spokesperson Sikhonathi Mantshantsha told Talk Radio 702 that the utility's board believed De Ruyter had brought the entity into disrepute.

De Ruyter's comments have also angered Mbalula, who on Thursday told the media that he had failed to fulfil the mandate given to him when he was appointed CEO.

According to Mbalula, this mandate was to turn around the state-owned enterprise, and not to talk politics.

He called De Ruyter "right wing" for commenting on topics that fell outside of his mandate as CEO.

Mbalula said SOE CEOs had no right to comment on open political debates because their personal views "distracted from their professional work".

"Mr De Ruyter was appointed strictly to lead the turnaround at Eskom into a functional public enterprise that provides the country with stable electricity. He has completely failed to deliver on this contractual obligation.

Instead, he shifts the goalposts by advertising his right-wing ideological posture on a matter that falls outside the scope of his employment contract," he said.

Mbalula was briefing the media at a post-Budget speech press briefing on Thursday in Cape Town.

He said the question of whether Eskom was privately or government-owned was not part of De Ruyter's contractual duty.

"That is the forte of the governing party and its ideological perspective on how best to ensure equitable access to electricity as a public good. We reject his baseless claims of alleged political meddling and corruption at the embattled power utility."

Mbalula questioned why De Ruyter was only raising corruption allegations when he was set to leave Eskom. He added that if the former CEO had any evidence of corruption, he should report it to the police, Hawks and the Special Investigating Unit.

He said the ANC would consider legal action against De Ruyter if he did not prove his allegations.

Former ANC national executive committee member and minister Derek Hanekom tweeted that if De Ruyter had any evidence of corruption and the involvement of certain ministers, he should expose it.

Minister in the Presidency Mondli Gungubele said De Ruyter portrayed a "right-wing" attitude in his interview on Tuesday.

Gungubele told Talk Radio 702 that the former CEO's comments reminded him of what apartheid officials used to tell "us".

De Ruyter has found some support among opposition political parties who believe the narrative that he was a victim of an unsupportive government. DA MP Ghaleb Cachalia showered him with praise, saying his tenure had seen an increase in maintenance, a dent in debt, and a renewable energy approach.

"We commend his bravery in which he lifted the veil on the large-scale corruption at Eskom. Mr De Ruyter is a true patriot. He pointed out that the ANC-aligned mafia remains embedded within Eskom under the protection of the ANC government," he said.

Meanwhile, Build One South Africa leader Mmusi Maimane said he would write to President Cyril Ramaphosa, demanding that he explain what he knew about the allegations by De Ruyter.

He would also write to the former CEO, urging him to reveal the mini...