South Africa's National Treasury intends to stick to a balanced fiscal stance under a coalition government, its director-general said on Tuesday, after the African National Congress (ANC) lost its majority in last week's election.

"I think that our fiscal strategy is achievable, even in a coalition environment ... because it's quite balanced," Duncan Pieterse told Reuters in an interview.

The ANC has up to two weeks to agree a coalition pact or another form of power-sharing arrangement with other political parties, after its share of the vote dropped below 50% for the first time in the post-apartheid era.

"A balanced macro-fiscal stance becomes more defensible in an uncertain political environment. And we intend to continue managing the fiscal stance along those lines," Pieterse said.

The ANC's potential partners diverge widely, from the free-marketeer Democratic Alliance (DA) to the more radical uMkhonto we Sizwe (MK) and the Economic Freedom Fighters (EFF), parties that advocate nationalising mines and banks and redistributing land.

South African markets rallied on Monday as investors bet on the ANC opting for a coalition including the DA rather than one involving MK or the EFF.