Roads Authority has temporary closed the Midima Road, a short route from Limbe to Mulanje, as a wooden bridge has been burned to ashes believed to be accidentally by a person with mental illness.
Spokesperson for the authority Portia Kajanga said engineers are already on site to rehabilitate the bridge.
"We are advising motorists to use the Limbe-Thyolo road if they want to go to Mulanje," said Kajanga.
The road is busy on Tuesdays because it is a market day at Nkando.
People around the area where the bridge has been burnt said a mentally challenged person sleeps underneath the bridge and usually uses fire to warm himself at night.
Kajanga said full maintenance works would start as the police investigate the real cause of the fire.