The ANC and its Women's League have demanded an apology from DA leader Helen Zille, accusing her of lying about not knowing that Telkom sponsored a The New Age breakfast briefing she attended.
"It is the view of the ANC that on numerous occasions Helen Zille has been found wanting when it comes to telling the truth," spokesperson Jackson Mthembu said in a statement on Wednesday.
"She has been masquerading as a so-called 'voice of reason' whilst she has been distorting the truth and misleading the public."
The Democratic Alliance said it would study the African National Congress's statement and respond later.
On Monday, Zille pulled out of a New Age Business Breakfast following reports that the event was funded with public money. She said she and other senior DA officials had previously spoken at the breakfast under the assumption that it was funded by The New Age and members of the public who bought tickets to attend.
"Now that it has come to light that the breakfasts are funded by public money via the SOEs [state-owned enterprises] to the tune of millions of rand, the DA cannot continue to participate."
In a statement explaining her decision, Zille said she pulled out after reading an article in City Press newspaper, in which it reported that Eskom, Telkom and Transnet spent millions on the sessions, while the SABC broadcast them free of charge.
"These breakfasts must be very profitable for The New Age, which is owned by the Gupta family, who are in turn vocal supporters and funders of the ANC and President Jacob Zuma.
"It is not acceptable or defensible for public money to be used to bankroll a privately owned newspaper, and indirectly the coffers of the ANC."
Asked during an interview with Eyewitness News whether she had thanked Telkom at a previous New Age business breakfast, in which she participated, Zille said she could not recall doing so.
"I cannot personally recall thanking anybody... but it was a very long time ago and I have many, many engagements every day," she said.
On Tuesday, The New Age released a video clip on its website of Zille thanking Telkom for sponsoring a New Age business breakfast in Cape Town in February last year.
Mthembu said: "Her [Zille's] lies bring into question the extent to which South Africans can take the Democratic Alliance seriously. This is proof that the DA cannot be trusted."
The ANCWL said Zille had revealed her "true deceitful nature".
"It is disgusting that the leader of the opposition can lie to the public with such ease, making such contradictory statements barely a year later when Zille released a statement denying she had any knowledge of who was sponsoring the event," ANCWL spokesperson Troy Martens said in a statement.
She said it had never been a secret who sponsored the breakfasts.
"It is a shame that Zille is trying to discredit these revolutionary and progressive sessions with her lies and deceit, irresponsibly acting as some kind of victim."