The Constitutional Court in the southern African nation of Malawi on Monday nullified the results of last year's presidential election, citing "widespread, systematic and grave” irregularities including significant use of correction fluid to alter the outcome.

A new vote will be held within 150 days, the court said, saying at the end that it hoped the ruling would not“destroy the nation.′

The two leading opposition candidates had challenged the narrow election win of President Peter Mutharika, alleging that irregularities affected over 1.4 million of the total 5.1 million votes cast.

Months of sometimes deadly unrest followed the announcement of the election results. The president and electoral commission acknowledged some irregularities but argued they were insufficient to affect the election's outcome.

Monday's ruling can be appealed to the Supreme Court.

Mutharika had been declared the narrow winner of Malawi's May election with 38% of votes, followed by Lazarus Chakwera with 35% and former vice president Saulos Chilima third with 20%. The four other candidates collectively got nearly 6%.

The five-judge panel heard arguments that the vote was rigged by the president and the electoral commission. Mutharika and the electoral commission acknowledged some irregularities but argued they were insufficient to affect the election's outcome.

The long-peaceful southern African nation has never had a presidential vote overturned.