Malawi opposition supporters celebrated overnight after a landmark court ruling which declared that incumbent President Peter Mutharika was “not duly elected” in a disputed 2019 vote.

The country’s constitutional court on Monday ordered a fresh vote within 150 days after it annulled the May election result over widespread irregularities, including the use of correction fluid on results sheets.

It had been feared that the verdict would stoke turmoil in the normally peaceful southern African country.

But there were scenes of jubilation overnight as opposition supporters chanted anti-Mutharika songs in the streets, sporadically setting off fireworks in the two largest cities Blantyre and Lilongwe.

“It is a good time to be alive in Malawi. We have demonstrated that democracy does and can work in Africa. And this victory is not for us, it is for generations to come,” said Lameck Hango, who celebrated with his friends in the capital Lilongwe.

Another Lilongwe resident, Johnson Banda, said he was “very happy with this judgement”.

“It’s a true indication that Malawi has true democracy and we really appreciate our court judgement.”

Businesses and shops re-opened on Tuesday after they pulled down their shutters the previous day fearing an outbreak of violence following the verdict.

Mutharika, 79, however, will remain president until the new election because he was in power before the now-invalidated 2019 result.

Sporadic protests had broken out across the country since the election in May, when Mutharika was declared the winner by a narrow margin, with 38.5 per cent of the vote.

Runner-up Lazarus Chakwera, who lost by 159,000 votes, said he was robbed of victory and took the matter to court.

It is the first time a presidential election has been challenged on legal grounds in Malawi since independence from Britain in 1964.

The European Union said in a statement that it “stands ready to accompany Malawi on the way ahead in view of preserving the unity and democratic credentials of the country”.

“We call upon all Malawians to respect the decision of the court and to adhere to the path outlined in Malawi’s constitution and electoral laws, including on the right to appeal,” said Tibor Nagy, the top US diplomat for Africa.

(AFP)