Money to support the newly launched political platform Agang SA comes from South Africans, its leader Mamphela Ramphele said on Tuesday.
"The decision to establish this party is a decision that is also accompanied by a determination that this must be a South African initiative, supported by South Africans," she told SABC Morning Live in an interview.
She said the financial support behind the party, which was launched in Johannesburg on Monday, was not from Americans, as had been insinuated.
Earlier on Tuesday, ANC secretary-general Gwede Mantashe reportedly said the new political platform could possibly be used to destabilise the country.
"The worry that we are raising... is that when these initiatives were announced, the founder was in the United States and announced that she is raising funding," Mantashe said.
Last year, Ramphele visited the United States to speak at Brown University.
She said that on her way back, she had met South Africans at a friends' cocktail party - as she had in other parts of the world.
"I went to Australia last year and briefed South Africans living in the diaspora... They are as much South African as we are," she said.
"The money we are currently using comes from South Africans, right here at home."
Ramphele said she intended using Agang SA to contest the 2014 national elections.