"We strongly believe that the one viable way forward in Zimbabwe is to have a rerun of the presidential election under full international sponsorship and supervision," he said in his 2008 State of the Nation address to parliament.
"That way, a repeat of the past run-off presidential election, which was declared by regional and international observers to be neither free nor fair and was characterised by intimidation and violence, can be avoided.
"It should be unacceptable for ruling parties to seek to manipulate election outcomes to extend their stay in power, as this is bad for democracy on our continent," he added.
Power-sharing talks between Zimbabwe’s ruling ZANU-PF and main opposition Movement for Democratic Change (MDC) have remained deadlocked over the distribution of key ministries.
Khana has been an outspoken critic of Zimbabwean President Robert Mugabe.
Botswana said in August that it did not consider Mugabe’s re-election in the June presidential rerun to have been legitimate.
The leader of Zimbabwe’s opposition MDC, Morgan Tsvangirai, pulled out of the second round vote in protest at what he said was a rising wave of government violence against his supporters.
He finished ahead of Mugabe in the first round, held in March.
The MDC won a majority in parliament in the March elections, leaving Mugabe’s ZANU-PF party in the minority for the first time since independence in 1980.
A total of 180 people were killed and about 9,000 injured in political violence since Zimbabwe’s general elections in late March, Amnesty International said in a new report Friday.
Zimbabwe’s political crisis has worsened its economic collapse. The country suffers the world’s highest rate of inflation, last estimated at 231 million percent.