President Mugabe has ruled Zimbabwe since independence in 1980
The outline of a deal has almost been reached for Zimbabwe's President Robert Mugabe to step down, opposition sources have told the BBC.
They say representatives of Mr Mugabe, military chiefs and the opposition have held meetings chaired by South Africa since Saturday's elections.
The sources said Mr Mugabe would make the announcement on television, but his aides have denied the reports.
Opposition leader Morgan Tsvangirai said he was prepared to wait.
In his first public appearance since the election, Mr Tsvangirai did not confirm the reported deal.
The leader of the Movement for Democratic Change held a news conference on Tuesday evening, but did not declare himself winner of the election.
"I prefer to wait until the ZEC [Zimbabwe Electoral Commission] confirms the results," Mr Tsvangirai said.
He said: "Robert Mugabe has said he's an honest man. I hope that when the results are announced it's a true reflection of the vote and that there's no reason to investigate fraudulent activities."
Claim and counter-claim
The opposition says it won Saturday's general elections, but results have been slow to emerge.
ELECTION RESULTS SO FAR
Breakaway MDC faction: 5
Yet to declare: 70
None so far
Winner needs more than 50% to avoid run-off
Results according to ZESN:
Morgan Tsvangirai, MDC: 49%
Robert Mugabe, Zanu-PF: 42%
Simba Makoni, Independent: 8%
Under the proposed deal, it has been claimed, Mr Tsvangirai would be declared the winner of the presidential race after Mr Mugabe publicly announced he was stepping down.
South Africa has also denied it is involved.
President Mugabe, 84, came to power 28 years ago at independence, but the economy has been in freefall in recent years.
The Zimbabwe Electoral Commission has not yet given any results in the presidential race, sparking MDC claims that the outcome was being fixed.
BBC correspondent Ian Pannell has spoken to three MDC sources who have claimed a deal had almost been reached.
The sources claim talks brokered by South Africa have been going on in Harare for the last few days, our correspondent says, although Johannesburg denies involvement.
The sources say Mr Tsvangirai's victory was so overwhelming that Mr Mugabe would have no chance of victory, even in a run-off.
But our correspondent cautions it is in the opposition's interests to talk up the possibility of Mr Mugabe's exit and the claims are difficult to verify at the moment.
Trained as a teacher
1961: Married Ghanaian Sally Hayfron
1964: Imprisoned by Rhodesian government
1980: Wins post-independence elections
1996: Marries Grace Marufu
2000: Loses referendum
2000: Land invasions start
2002: Wins presidential polls, dismissed by observers
Bright Matonga, Zanu-PF's Deputy Information Minister, denied any talks were going on with the opposition.
"There are no discussions, no negotiations, and President Mugabe will not be going on state television to announce anything because there's nothing to announce."
Earlier, there had been increasing speculation that a second round vote would be needed, as no candidate had yet passed the 50% threshold required for victory.
The MDC says that Mr Tsvangirai won 60% of the vote, against 30% for Mr Mugabe.
Parliamentary results released so far show that the MDC has 72 seats, including five for a breakaway faction of the party, against 68 for Zanu-PF, with 70 still to come.
As he cast his vote on Saturday, Mr Mugabe said:
"If you lose an election and are rejected by the people, it is time to leave politics."
Mr Mugabe has not been seen in public since the election.