The Economic Freedom Fighters (EFF) on Tuesday said it would petition the Supreme Court of Appeal after the High Court in Johannesburg dismissed its application for leave to appeal former finance minister Trevor Manuel's defamation ruling.
The red berets on Tuesday lost the appeal that directed them to apologise to Manuel and pay R500 000 in damages.
EFF secretary general Godrich Gardee said his party will "go to the highest court in the land" to seek justice.
"We intend exercising our rights and petition the Supreme Court of Appeal within 24 hours. We think that the lower court has erred and disregarded certain facts on the matter and actually misapplied the law," Gardee said.
Manuel took the EFF to court after the party claimed nepotism in the search and appointment of the new South African Revenue Services commissioner Edward Kieswetter.
Finance Minister Tito Mboweni appointed a panel, headed by Manuel, to search for a replacement for the embattled Tom Moyane. Kieswetter was subsequently appointed tax boss in March this year. The red berets labelled the appointment as "corrupt" and questioned the secrecy of the interviews and appointment process.
In handing his judgment on May 30, Judge Elias Matojane said the EFF's remarks were unlawful, false and defamatory. The party, led by Julius Malema, was instructed to apologise to Manuel and remove all defamatory remarks from all its platforms, including social media.