Pop diva Madonna has weighed in on Malawi's chaotic election, criticizing embattled President Joyce Banda, who has tried to nullify the vote amid allegations of irregularities.

The superstar, who adopted two children from the southern African nation, has been involved in a long-running spat with Malawi's government over her charity work in the country.

A week after Malawians went to the polls to elect a new president the result is still not known and fierce legal wrangling has raised the prospect of a protracted political crisis.

With at least 90 percent of the votes counted over the weekend, it was unclear if election watchdogs would release the results on Monday, and if the outcome would be recognized.

Malawi's President Joyce Banda on Saturday declared this week's chaotic election "null and void" and called for a fresh vote, but the high court rejected the decision.

Banda, who has claimed there were "serious irregularities" with the poll, declared fresh elections should be held within 90 days but said she would not stand as a candidate, to "give Malawians a free and fair" election.

Malawi's President Joyce Banda on Saturday declared this week's chaotic election "null and void" and called for a fresh vote, throwing the impoverished nation into crisis.

Banda, who has claimed there were "serious irregularities" with the poll, declared fresh elections should be held within 90 days but said she would not stand as a candidate, to "give Malawians a free and fair" election.

Malawi's high court has thrown out President Joyce Banda's application to block the release of election results, as counting continued at a snail's pace three days after the chaotic vote began.

Banda's People's Party (PP) had alleged that "figures that are coming from the districts tally centers are not matching with the number of voters from different polling stations because the system has been hacked," according to a court affidavit.

Malawi's President Joyce Banda said there had been "serious irregularities" in the conduct of this week's election, questioning the legitimacy and outcome of the poverty-stricken nation's highly-charged vote.

Banda said the vote has seen ballot tampering, presiding officers arrested, people voting multiple times and the collapse of the computerized voter counting system.

Voting in Malawi spilled into a second day Wednesday after riots sparked by the late opening of polls marred an election seen as a test of President Joyce Banda's scandal-tainted rule.

The military was deployed Tuesday after irate voters burned polling stations amid allegations of rigging when some bureaus opened 10 hours late.

Malawi's President Joyce Banda wrapped up her election campaign Saturday by claiming that a graft scandal which rocked her administration is in fact her trump card.

As part of her campaign to crack down on corruption, she last year ordered an audit which found that millions of dollars in state funds had been looted by officials under her watch.

Malawi police said on Monday an officer was axed to death and one person shot dead in clashes with stone-throwing opposition activists after a weekend rally by President Joyce Banda.

Police spokeswoman Rhoda Manjolo told AFP police had to fire in "self defense" after a hostile crowd attacked the officer. One demonstrator was shot and killed.

Malawa's President Joyce Banda admitted Friday she took a "political risk" in launching a major fight against corruption ahead of elections in May.

In late 2013 Banda dissolved her entire cabinet, sacking four ministers, amid allegations top government officials embezzled millions of taxpayer dollars.