The IFP and NFP thanked voters on Thursday for taking part in by-elections in KwaZulu-Natal.
Inkatha Freedom Party provincial leader Blessed Gwala said in a statement that voters had stirred up a sense of victory in the party.
"The IFP is very excited by the results of yesterday's by-elections, but also extremely humbled by the trust that the people have placed in the IFP," he said.
National Freedom Party leader Zanele KaMagwaza-Msibi said she doubted the fairness of the by-elections.
"We are grateful to our members who braved threats and intimidation and showed their... [loyalty] to our party," she said.
The IFP won KwaZulu-Natal wards previously held by the African National Congress and the NFP, according to the by-election results released by the Independent Electoral Commission on Thursday.
The party won Ward Two, in Hlabisa, which was previously held by the NFP.
Since last year's local government elections, Hlabisa had been run by an ANC-NFP coalition.
Gwala said the IFP was grateful to those who had voted for it in Hlabisa.
"Your victory shows [that] the IFP elephants are indeed on the march to victory in the province of KZN in 2014," he said.
KaMagwaza-Msibi said it "pains" her that the NFP lost in Hlabisa by five votes.
"However, we are aware of shenanigans like 'importing' voters from other wards to vote during by-elections, that are being done by our rivals during all by-elections."
The IFP retained Ward 39 in KwaMashu, Durban. The IFP and NFP have been at loggerheads in the ward since early August.
At least five IFP supporters or members, and the son of an NFP leader, have been killed in the area since then.
The ward was previously held by the IFP's Themba Xulu. He was found shot dead in Inanda on October 7 after being abducted from his home two days earlier.
KaMagwaza-Msibi said the by-election in the ward would have been fair had there not been intimidation by the IFP.
"Because of incidents of intimidation, most of our supporters did not come to cast their vote as they feared that they will be attacked."
The IFP snatched Ward Four, in Nkandla, from the ANC.
Nkandla, which is President Jacob Zuma's hometown, has recently been in the public eye after it emerged that the president's private residence was undergoing a reported R200-million upgrade.
Gwala said the Nkandla victory was "sweet".
"The people of Nkandla can obviously tell the difference between 'community' development and service delivery for all, as opposed to 'individual' development and self-service," Gwala said.
"We thank the people of Nkandla and we look forward to the broader consequences of this result."
National IFP spokesperson Mbongeleni Joshua Mazibuko said the by-election results were "irrefutable proof that the people of KwaZulu-Natal have matured politically beyond being hypnotised by ANC's dirty tricks of using government resources to win votes."
The ANC retained Ward 72 of the eThekwini municipality.
Ward Three in the Msukaligwa (Ermelo) municipality, in Mpumalanga, which was held by the ANC, was uncontested.
The ANC also retained Ward 22 of the Lukhanji (Queenstown) municipality in the Eastern Cape, and Ward 12 of the Setsoto (Senekal) municipality in the Free State.
The Democratic Alliance retained Ward Two of the Bitou (Greater Plettenberg Bay) municipality in the Western Cape.