Cyclone Idai and Cyclone Kenneth struck just six weeks apart, flattened cities and villages and, in the case of Idai, which crashed into Mozambique's central region in March, prompted devastating floods in one of the worst weather-related disasters to hit the southern hemisphere.

Speaking to reporters after meeting Mozambique's President Filipe Nyusi in the capital Maputo, Guterres said the cyclones were a consequence of climate change - a phenomenon Mozambique is on the frontline of but does not contribute to.

"This gives me the right to demand the international community double its efforts," he said, noting that appeals for post-cyclone aid have gone underfunded.

An emergency UN appeal for Mozambique following Idai received less than half of the $282 million requested, while donors at a pledging conference in the cyclone-hit port-city of Beira raised $1.2 billion for reconstruction - again less than half of the $3.2 billion Mozambique says is required.

Idai, one of the worst storms on record to hit Mozambique, pummelled Beira before moving inland, killing a total of 1,000 people across Mozambique, Zimbabwe and Malawi.

Kenneth hit further north with winds of up to 280 kph (174 mph), killing around 45 people and reducing rural villages to piles of wood and palm fronds.

It marked the first time two powerful cyclones had struck Mozambique in the same season, destroying homes, infrastructure and crops in areas where many already lived in poverty. Climate change is expected to see the country increasingly exposed to such extreme weather.

The country's north, where Kenneth hit, is also struggling with a nascent Islamic insurgency, which has seen militants kill over 100 people and which complicated the relief effort in the aftermath of the storm.

Guterres said the United Nations would help Mozambique prevent young people from becoming radicalised, including by providing experts to support the country in communicating with disenfranchised groups.