Allegations of a second instance of censorship within a week at the SABC were disturbing, the Cape Town Press Club said on Friday.
The SABC was being investigated for cancelling a MetroFM talk show on Tuesday about media coverage of the ANC's elective conference in Mangaung.
The broadcaster also allegedly censored a talk-show on SAFM on Wednesday morning.
"Allegations have now surfaced that a talk-show on SAFM on Wednesday was also cancelled at the last minute in a similar fashion," the club said in a statement.
"Presenter Siki Mgabedeli was due to interview Cosatu [president] Sdumo Dlamini, but an instruction was given apparently to cancel the discussion because the interview did not have an ANC participant."
The club said in the space of a week both the media and an alliance partner of the ANC had been on the receiving end of censorship within the SABC.
The club welcomed the Independent Communications Authority of SA's probe into the cancellation at MetroFM, and hoped the probe would be expanded to include the allegations about censorship at SAFM on Wednesday.
On Tuesday, three political journalists were scheduled to appear on MetroFM's "Talk with Sakina", presented by Sakina Kamwendo, to discuss media coverage of the conference in Mangaung. The talk was cancelled at the last minute.
Sunday Times political editor S'thembiso Msomi, Business Day political editor Sam Mkokeli and Financial Times Southern African bureau chief Andrew England were reportedly already at the SABC studios when the interview was cancelled.
SABC group radio executive Leslie Ntloko said on Wednesday that management had received the list of guests for the cancelled segment late. When management learned the ANC was not participating, the plug was pulled. He said the ANC needed to be a part of the discussion.
He cited SABC rules that when an issue involved an event of national importance, and a political party, that party had to be invited to participate.
SABC spokesperson Kaizer Kganyago was not immediately available for comment.