Mugabe told his countrymen that liberation war veterans were preparing to take up arms if the Movement for Democratic Change wins the presidential runoff, the Times of London reported.
The state-owned Herald newspaper said Mugabe told the veterans that he did not want to go back to war but insisted Zimbabwe would never be ruled by the MDC.
"It will never happen that this land which we fought for should be taken by the MDC so that they can give it back to our former oppressors, the whites," the newspaper quoted him as saying.
Mugabe's Zanu PF party already is accused of waging a pre-runoff campaign of arrests and intimidation against political opponents. MDC leader Morgan Tsvangirai, who beat Mugabe in the March election, but not by enough to escape a runoff, was arrested four times in the past week. The MDC secretary-general, Tendai Biti, faces a treason charge.
Zanu-PF activists are accused of killing 66 MDC supporters in an attempt to steal the June runoff vote, while human rights groups have been forced to close shop or leave the country.