“The opposition will table an opposition report to coincide with the ANC’s own study group report to be tabled in Parliament after 24 October,” he told reporters in Johannesburg.
Maimane said South Africa’s Constitution was under threat.
“The opposition will not stand by while the Constitution is being vandalised.”
He said the opposition needed to take “strong and deliberate steps”.
The committee was nothing more than an “ANC study group” and might as well conduct its meetings at African National Congress headquarters Luthuli House, rather than in Parliament, he said.
Maimane said the ANC would go to any length to protect President Jacob Zuma from taking accountability for the R246 million spent on his private Nkandla homestead in KwaZulu-Natal.
“All those who’ve been made scapegoats can come out and tell the truth.
“It will be a constitutional crisis if the ANC study group is allowed to ramp their report through Parliament.”
United Democratic Movement leader Bantu Holomisa, Congress of the People leader Mosiuoa Lekota, and Economic Freedom Fighters leader Julius Malema were also in attendance.
The opposition withdrew from the committee in protest at the ruling party’s refusal to enforce Public Protector Thuli Madonsela’s finding that Zuma should pay for part of the project.