The death toll from Tropical Cyclone Freddy has passed 300 people as the body count continues to rise, with authorities in Mozambique taking several days to assess the extent of the damage and loss of life.

The storm tore through southern Africa at the weekend for a second time after first making landfall in late February.

It is one of the longest-lasting tropical cyclones ever recorded and one of the deadliest in Africa in recent years.

At least 53 people have died in Mozambique's Zambezia province, authorities said late on Wednesday, more than doubling their previous count.

The storm had killed about 27 people in Madagascar and Mozambique before lashing Mozambique for a second time.

Malawi has reported 225 dead so far, with hundreds more injured and some still missing.

As Malawian families gathered to bury the victims, President Lazarus Chakwera called on the international community for support.

"We are using hope as our currency to encourage those that have survived that we will not leave them alone because we are trusting you, as our international neighbours to come through so Malawians can continue with that hope," he said, adding that survivors needed clothing, food and shelter.

The United Nations Refugee Agency said it was deeply concerned by the devastation and impact of Freddy which affected more than 16,000 people across 10 districts in Malawi's southern region.

Continued rain and power outages have hampered search and rescue efforts this week, as the storm caused severe flooding, swept away roads and left bodies and houses buried in mud.