Residents in central Mozambique were on Thursday bracing for a tropical cyclone described as "extremely dangerous" by weather experts, with imminent landfall expected near the port city of Beira, which has a population of about 530,000 people.

"This storm has already triggered torrential rainfall that's led to over 100 fatalities in southern Malawi and Mozambique," according to Derek van Dam, reporting for CNN.

Storm Report SA said Cyclone Idai had regained major intensity during the night.

"Travelling at a speed of 11kmp/h, with sustained winds of 195kmp/h and gusting at 240kmp/h, she now is once again an extremely dangerous cyclone," said Storm Report.

Hurricane/Typhoon/Cyclone Alerts shared this on Facebook: "All people/friends in Mozambique from Inhassoro to Quelimane, are urged to prepare for intense cyclone conditions including torrential tropical squalls, life-threatening coastal and inland flooding and 185-220 kph winds and a 3-5 meter storm surge."

It advised residents to seek shelter or to evacuate in preparation for Cyclone Idai, which was due to make landfall on Thursday in Sofala province, near Beira.