Malawi's electoral board on Friday said it was suspending updates of results from this week's elections in order to resolve complaints raised by some of the parties.
A count of votes tallied in three-quarters of the country's polling stations, released Thursday, found incumbent president Peter Mutharika leading with 40.9 percent.
His closest challenger Lazarus Chakwera of the Malawi Congress Party had 35.44 percent of the vote.
"At this point, the commission will not be providing an update on the status of results because announcement of results is interlinked with the resolution of complaints and concerns," electoral commission chairwoman Jane Ansah said.
She said her commission had received 147 complaints. The elections on Tuesday chose a president, lawmakers and municipal councillors, and the complaints related to all three tiers.
The electoral body has to announce the final results within eight days of voting.
"The commission is utilising every moment, day and night to ensure that we provide a credible outcome of the polling process," Ansah said.
"We will make sure that every vote that has been counted at the polling station is counted in the national tally."
The most prominent complaint was that figures on result sheets had been altered by correction fluid, incidences the electoral body said were widespread across the country.
"Our legal team is expediently reviewing all the complaints received and giving feedback to the complainants," she said.
Chakwera on Wednesday warned of alleged attempts to rig the vote, saying his MCP had conducted its own count and this, he maintained, showed he was ahead.
The European Union observer mission has described the vote as "well-managed, inclusive, transparent and competitive".
But it said that tension during the campaign "was not helped by various claims of 'rigging'".
The southeastern African country has around 6.8 million potential voters, with more than half aged under 35.
Turnout data has not been published.