Mr Mugabe told a rally in Chinhoyi, 60 miles from the capital, that whites were establishing litist, racist clubs to keep out blacks. He threatened unspecified action. His Zanu-PF party, which has been in power since independence in 1980, is certain to win the election.
Mr Nkomo said the government would take stern action against any whites who failed to toe the line after the election. He accused them of lack of respect for state structures and of forming exclusive "governments" of their own to run their affairs. "If something goes wrong on a white man's farm, he will never report to government but to his association of whites only," Mr Nkomo said in the south-western town of Gwanda.
Zimbabwe's splintered opposition parties have failed to capitalise on the country's economic woes as a platform on which to fight Mr Mugabe.
"There are no economic issues at stake in this election, no awkward questions to answer as far as Zanu-PF is concerned, because the opposition is the main subject," said John Makumbe, of the political science department at the University of Zimbabwe.
Many Zimbabweans consider the elections a formality. Zanu-PF won 45 out of 120 parliamentary seats by default when the opposition failed to register candidates by the deadline last month. Some opposition candidates also dropped out.
The opposition, with only three seats in the outgoing parliament, is expected to win at most seven from its field of 61 hopefuls; 30 independents are also running.
Twenty seats in Zimbabwe's 150-member parliament are filled by presidential appointees and 10 others by traditional chiefs.