Bakili Muluzi has been a bitter foe of the incumbent
One of Malawi's opposition leaders has accepted that President Bingu wa Mutharika won Tuesday's elections but another has claimed widespread rigging.
Ex-President Bakili Muluzi has telephoned Mr Mutharika, with whom he has fought a bitter feud in recent years, to offer his congratulations.
But Mr Muluzi's ally and main opposition presidential candidate John Tembo claims there was election fraud.
With 40% of votes counted, Mr Mutharika has a huge lead, official results show.
The Democratic Progressive Party (DPP) leader, a 75-year-old former World Bank official, has 1.3m votes against 0.5m for Mr Tembo.
Final official results are expected on Thursday night, a day before the winner of the presidential vote is due to be inaugurated.
In the parliamentary vote, Mr Mutharika's party also has a clear lead, with nearly half the ballots counted.
With 193 seats up for grabs, partial official results have the DPP winning 59; Mr Tembo's Malawi Congress Party (MCP) 17; Mr Muluzi's United Democratic Front (UDF) 10; and the Malawi Forum for Unity and Development just one. Eleven seats have gone to independents.
Mr Muluzi was barred last Saturday from seeking a third term and his UDF instead backed Mr Tembo.
Mr Muluzi told Malawian media: "As a former president of this country, I'm saying: 'Let's move forward.'
"I telephoned him [Mr Mutharika] this morning, we had a conversation and I conveyed my congratulations to him for the victory and wished him well and his DPP party."
But Mr Tembo, 77, struck a very different note, describing the results as "very unusual".
He told a press conference: "If the population of a country is 50 million and the results indicate that 54 million have voted, you would consider them [results] extraordinary wouldn't you?
"I just wanted to indicate that, so when you get to know the full extent of my complaint it must be on the basis of what I'm telling you - that the results are absolutely unbelievable."
On Wednesday, the MCP disputed results in its traditional stronghold of Central Province, saying its poll agents had been denied access to counting centres in the area.
International poll observers said the president had enjoyed an unfair advantage, including a partisan state media.
John Tembo (l) has not accepted that President Mutharika (r) has won
EU observer group head Luisa Morgantini said the Malawi Broadcasting Corporation and Television Malawi had failed to provide balanced coverage of the campaign.
Former Ghanaian President John Kufuor, leader of the Commonwealth observer team, said: "We are extremely concerned at the conduct of state-owned media in its coverage of these elections."
The election followed a five-year feud between Mr Mutharika and his predecessor Mr Muluzi that brought a failed impeachment bid, parliamentary deadlock and coup plot claims.
Mr Mutharika was elected on a UDF ticket in 2004 but he then fell out with Mr Muluzi, accusing his one-time backer of trying to stonewall an anti-corruption drive.
The president quit his rival's party in 2005 to form the DPP and lead a minority government.
Poverty, agriculture and health care are the big issues for Malawi, where two-thirds of the 13 million population lives on less than $1 a day and Aids has orphaned an estimated one million children.
I am very impressed with how the elections have been conducted. They were peaceful and orderly. Mr Muluzi has shown maturity and all peace loving Malawians including myself are happy with the gesture he has shown, by congratulating Bingu.
There is no confusion in Malawi. The elections have been very smooth, free and fair. This thing that you are hearing that John Tembo is disputing the results is small storm in the tea cup. He is the kind of politician who has never conceded defeat in political circles.
Clement, Tokyo, Japan
I am not happy with the election results. Even the President himself knows that there is something wrong with these elections. Check on the final tally of the results which have been counted against the voters registered in those areas. I am ashamed of myself to be associated with this.
Peter, Blantyre, Malawi
I think its a good move on the part of Muluzi, the only good thing he has done in a while. It would even be better if he could just bow out of politics for good, ave himself some disgrace as a former president. As for JZU Tembo, he is just acting like a wounded lion he knows he has beaten fair and square. But as a good soldier you don't want to die crying, you would rather waste a few bullets before conceding to death.
Robert, Blantyre, Malawi
I find it very odd that Mr Muluzi finally decides to accept that President Mutharika will always be the best choice for the average Malawian. I mean, after so many insults and comments, it just does not add up. Maybe the rumours are true, "Atcheya" as they call him, has finally gone mad.
Wiza, Blantyre, Malawi
To the extent of having the former president Bakili Muluzi, who happens to be the most stubborn and non-understanding body, conceding the results, it only shows to me that the ex-president is developing some sense of humanity. This is what we were expecting amid the fears that may be we'll be having chaotic situations after the polls. But that isn't so.
Kingsley, Mzuzu, Malawi
I want to congratulate all Malawian People for having voted wisely in a democratical way. Actually I am a Rwandese by nationality and I am 35 years old but this is my first time to see free elections where people can vote so freely. I think my President his Excellency Paul Kagame can learn much from what happened here in Malawi. Let me say it again if Dr Bingu wa Mutarika has won, he has won. Nothing behind it. My God bless him.
Emmanuel, Lilongwe, Malawi
Why do you always focus on the negative when it comes to reporting issues concerning Africa. Malawians are peace loving people and we have just conducted one of the most successful elections! There is no truth in Mr Tembo's allegations. Are you implying that the International Observers are incompetents? It is a fact that Tembo has lost in his previous stronghold. Where were the over 5,000 independent monitors when the alleged rigging was happening? Mr Tembo knows why he lost and he should just accept the results. Malawians were tired of how irresponsible the previous opposition dominated parliament was.