A new South African party has lodged a complaint with election officials accusing the ruling African National Congress (ANC) of intimidation.
The Congress of the People (Cope) says the ANC has disrupted its rallies.
Cope deputy leader Mbhazima Shilowa told the BBC the ANC had bussed in supporters, blocked access and tried to drown out speeches with loud-hailers.
The ANC, which is widely expected to win this month’s general election, has not yet commented on the accusations.
Mr Shilowa said that the level of intimidation made it impossible to describe the general election as free and fair.
He said in several areas “the ruling party has determined that any other party will not be allowed to campaign”.
“I therefore cannot continue to say that the poll will be free and fair.”
Cope was formed after Jacob Zuma was chosen to replace Thabo Mbeki as leader of the ANC.
A group of ANC members largely loyal to Mr Mbeki have built Cope into a party that analysts say is providing a stiff challenge to the ANC.
But this month’s election is still expected to return the ANC to power, albeit with a reduced majority.