A statement from the presidency said General Vincent Nundwe was replaced by the former air force commander, Major General Andrew Lapken Namathanga.

Nundwe will be assigned to other duties in the public service, the statement said.

The move comes days after Mutharika dissolved his cabinet, his latest political move after his May re-election was annulled over irregularities.

In a landmark ruling last month the Constitutional Court ordered officials to hold a fresh presidential poll within 150 days in the poor southern African nation.

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

Mutharika is attempting to quash new balloting that would require him to win more than a 50 percent majority to secure a second term.

He has refused to ratify new electoral laws and filed an appeal against the court's decision to nullify election results that had declared him the winner with just 35.8 percent of the vote.

A retired army general suggested that the army reshuffle was linked to Mutharika's uncertain political future.

"He wants to put people who work for his interests and from his home area," said the former senior official who asked not to be named.

"Discipline (in the army) will be highly compromised," the general said.

Mutharika has replaced the army chief four times since his election in 2014.

After Nundwe was appointed as army commander last June he won praise for the army's handling of six months of protests over Mutharika election victory.

The military stepped in as confrontations between police and protesters turned violent.