The National Union of Mineworkers' (NUM) will not apologise to the Association of Mineworkers' and Construction Union (Amcu), spokesperson Lesiba Seshoka said on Thursday.
"We are not going to apologise to anyone, not today, not anytime soon," he said.
He was responding to Amcu's demand that the union publicly retract accusations that Amcu was responsible for the killing of NUM members in Rustenburg.
"We do not owe anyone [an] apology. We are not the chamber [of mines], we are a trade union under Cosatu [Congress of SA Trade Unions]."
Earlier in the day, it was reported that Amcu walked out of talks to form a centralised bargaining forum for the platinum industry, demanding that NUM retract its accusation.
Amcu's protest followed news reports on Tuesday in which NUM president Senzeni Zokwana appeared to blame Amcu for the recent killing of a NUM branch chairperson and a relative of a shop steward.
Zokwana was quoted as saying it was strange that only NUM leaders who were being shot after a peace accord was signed.
"Amcu never signed the accord. The only way Amcu can outsmart NUM in organising is through intimidation and violence."
Amcu president Joseph Mathunjwa said his union wanted a public retraction.
"How can we stabilise the industry when one of the parties at the table goes to the media and accuses us of assassinations of their members?" he was quoted as saying.
Amcu's secretary Jeff Mphahlele declined to comment on whether his union would go back to the negotiations.
"I am at another meeting, please call Jimmy Gama [Amcu's treasurer]."