A family is seen outside their house which got damaged by Cyclone Kenneth in Ibo island north of Pemba city in Mozambique. Picture: Tsvangirayi Mukwazhi/AP

Maputo - Cyclone Kenneth has displaced around 21,000 people since it hit last week causing "unspeakable" damage, the International Organization for Migration said Friday.

More than 40 people were killed after Cyclone Kenneth made landfall causing heavy flooding. It was the second major storm to hit the Southern African country in about a month.

"The damage caused by Cyclone Kenneth is unspeakable," said IOM Mozambique Chief of Mission Katharina Schnoering. "The area is heavily affected; thousands of families are displaced with their homes and livelihoods destroyed."

The IOM statement said around 21,000 people in northern Mozambique had been displaced and were either living in accommodation centres or staying with host families.

A house damaged when Cyclone Kenneth struck Ibo island north of Pemba city in Mozambique. Picture: Tsvangirayi Mukwazhi/AP

"When the cyclone first hit, in the heavy rain and wind, the entire settlement around our house started to slide away. We ran for our lives. Everything that we had, our home and belongings are gone, all gone," the IOM quoted one displaced woman, Maria Semao, as saying.

The government of Mozambique says about 200,000 people in total have been affected by the latest cyclone. The IOM has been delivering shelter kits to those left homeless.

When another cyclone, Idai, hit in March, hundreds of people were killed and tens of thousands displaced. It also affected Malawi and Zimbabwe.

Also on Friday, the World Bank announced it was releasing some 700 million dollars to help the three Idai-hit nations.

"Together, total World Bank support to the three countries' recovery reaches around 700 million dollars," the body said in a statement.

Gemma Connell, the head of the UN's regional humanitarian response, said she expected a high likelihood of food insecurity in the coming months, as those affected are among the poorest people in Mozambique and the world.

An elderly woman walks past a house damaged by Cyclone Kenneth when it struck Ibo island north of Pemba city in Mozambique. Picture: Tsvangirayi Mukwazhi/AP

In coastal communities where people rely on fishing as their livelihood, some are using mosquito nets to catch fish as their equipment has been destroyed, she said.

"This will be a long recovery," Connell said, speaking to reporters in New York via phone link.

Connell called for global action to help the humanitarian effort, as well as moves to mitigate the impact of climate change, which has led to more frequent severe weather events including cyclones Idai and Kenneth.