South Africa's Democratic Alliance (DA) will do its utmost to prevent a coalition between the African National Congress (ANC) and the Economic Freedom Fighters (EFF) or uMkhonto we Sizwe (MK) parties, party figure Helen Zille told Reuters on Thursday.

"We will do everything in our power to prevent an ANC, MK and EFF coalition. That would spook investors, it would tank the economy it would be a disaster for South Africa. So we are very committed to prevent that outcome," said Zille, a former DA leader who is chairperson of the party's federal council.

Partial results show the ANC on course to lose its parliamentary majority after 30 years in power, with the DA expected to come second, the EFF third and MK fourth.

"We are not in negotiations with anybody," said Zille.

Asked about what coalition options her party might pursue, she said: "My expectations are that my party will take the least bad option."