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Cape-Town-based Majavu, who is a former spokesperson for the SA Municipal Workers Union, was blacklisted in August last year.
Executive director of communications and research Ross van der Linde confirmed that the party had cut communication with Majavu.
"Majavu is not a journalist. Some journalists and editors disagree with our policies and views, and they are entitled to do so. But Anna Majavu is a former South African Municipal Workers Union spin doctor, who has a particular political agenda," Van der Linde said.
He said the DA was not obliged to send information to any individual or organisation.
Majavu has rejected the DA's assertion, saying she is a professional. She said her woes started when she wrote a story about how DA MP Pieter van Dalen shot at two children in Khayelitsha.
Majavu based her story on a report by Advocate Pierre van Tonder, who adjudicated in the matter of an appeal by a Metro police officer who was dismissed.
The officer, with Van Dalen, shot rubber bullets at two children playing soccer in Khayelitsha late at night.
Van Dalen - who was a councillor at the time of the incident - accompanied Metro police officers during the xenophobic attacks in 2008.
The DA lodged a complaint with the press ombudsman about the story. Among other things, the party objected to the reference to "black" children in the story. In its defence Sowetan argued that it was common knowledge that Khayelitsha was not a racially integrated area - so it would be reasonable to conclude that the children were black. The ombudsman dismissed the DA's objection.
"The DA took me off their press list the same day they filed a complaint with the press ombudsman, and not because of my previous job," Majavu said.
"It is unfortunate that the DA chose to go this route. History shows that the exclusion of journalists is used as a form of censorship against those who do not mollycoddle their subjects. It is no different from Julius Malema kicking out a journalist from a press conference", Sowetan acting editor Thabo Leshilo said.
Rhodes University's Jane Duncan said the DA's refusal to send her information was childish.
"Majavu's previous work is irrelevant. Many journalists have been involved in other professions in their working lives. This does not make them lesser journalists, otherwise one would need to be a journalist from the cradle to the grave to qualify in the DA's eyes, which is unrealistic."