The election body said it is expecting to complete a partial recount on Monday.
Utoile Silaigwana, the deputy chief elections officer, said on Sunday that once the recounting ends "we will immediately start the verification of the presidential vote".
"So what I am saying is that the end of the recount will kick-start that verification," he said.
"It may be Tuesday or any other day. The chief elections officer will then write to the candidates inviting them to the verification process."
Critics, including Britain, rights groups and the US, have blamed Mugabe for violence against opposition supporters since the election and have urged him to let the results be published.
The US envoy for Africa on Sunday threatened Zimbabwe with UN sanctions if the post-election crisis was not resolved soon.
|The US says opposition leader Tsvangirai |
should head any new government [AFP]
Jendayi Frazer had earlier called for an end to the violence in Zimbabwe and said Morgan Tsvangirai, the MDC leader, should head any new government, dismissing the prospect of a second round run-off.
Frazer has been on a tour of the region, which began in South Africa, to put pressure on Robert Mugabe to step down as president.
She has met South African officials and the presidents of Angola and Zambia.
The UN Security Council will discuss the Zimbabwe crisis on Tuesday, with permanent members Britain and the United States ratcheting up the pressure on Mugabe, who has ruled for 28 years.
During the verification process, candidates, their proxies and observers will compare ZEC figures with those they have compiled themselves from polling stations.
Only after all parties agree with the figures can the ZEC announce a final result.
If a candidate wins more than 50 per cent, he is declared winner. If no one has a majority, the ZEC will announce the final result and call a run-off within the following 21 days.
Nelson Chamisa, a spokesman for the opposition Movement for Democratic Change (MDC), said "obviously there will be a lot of debate about figures which will delay the announcement of the results" further.
"That is what Zanu-PF wants and in the meantime they continue with their reign of terror. The question is, what was ZEC doing with those figures all this time?" he said.
The MDC has accused the ruling Zanu-PF party of attacking opposition supporters to intimidate them before an expected run-off.
Tsvangirai, the MDC's presidential candidate, says he won the presidency outright and accuses incumbent Mugabe of using the delay to rig victory in a run-off.
Tsvangirai has said he would not accept a run-off unless it were supervised by the United Nations.