Mozambique and Malawi were calculating on Monday the damage caused by Tropical Storm Freddy, which crossed southern Africa for the second time in a month over the weekend, leaving a trail of destruction and killing at least 17 people.

Freddy is one of the strongest storms ever recorded in the southern hemisphere and could be the longest-lasting tropical cyclone, according to the World Meteorological Organization.

It hit central Mozambique on Saturday, tearing roofs off buildings and causing widespread flooding around the port of Quelimane, before moving inland towards Malawi with torrential rains that caused landslides.

The full extent of the damage and loss of life in Mozambique, in particular, is still unclear, as the power supply and telephone signals have been cut off in some parts of the affected area.

In Malawi's second largest city, Blantyre, at least 11 people have died and 16 are missing, police spokesman Peter Kalaya told Reuters, adding that it was likely that these figures would rise, since so far there have only been victims in Blantyre and the storm had affected 10 districts.

He said rescue teams were searching for people in Chilobwe and Ndirande, two of the worst-affected areas of Blantyre, where it was still raining on Monday and many residents were without power.

"It is feared that some missing people are under the rubble," said Kalaya.

At least six people died in the port of Quelimane, which was right in the eye of the storm, the authorities announced this Monday on public broadcasting.

The total death toll from Storm Freddy in Mozambique, Malawi and Madagascar since it first hit last month is now at least 44.