The United Nations senior relief official on Friday warned of an extreme weather emergency and called for actions to be taken to address climate change to avoid recurrent flooding in South Sudan.

Arafat Jamal, acting humanitarian coordinator in South Sudan said further investment in disaster risk reduction and climate change adaptation is required to avoid a repeat of seasonal flooding in the world's youngest country.

"More than 780,000 people have been affected since May, with at least 77 percent of those affected being in Jonglei, Unity, and Upper Nile states," Jamal said in a statement issued in Juba.

He said the entire communities were forced to move to higher ground to escape the floodwaters.

Flood-displaced people, many of whom are highly vulnerable, uprooted earlier by sub-national violence and the 2020 floods, are again now displaced, Jamal added.

He said the UN recently released 20 million U.S. dollars from the South Sudan Humanitarian Fund, with part of the allocation supporting flood response efforts and complementing bilateral funding sources.

Earlier this year, work was done in the preparedness and prevention phase to mitigate the impact of floodwaters ahead of time by repairing and maintaining dykes in parts of Jonglei, said Jamal.

South Sudan is ranked among the five countries in the world most vulnerable to the impacts of climate, and the South Sudanese are already dealing with the consequences, the UN said.

Food insecurity is at record levels as the country regularly experiences torrential rains, seasonal flooding and locust infestations, and it is the most vulnerable people who suffer the most.

"The people of South Sudan are on the frontline in the fight against climate change. We need to work together with affected people and local governments to rehabilitate infrastructure in flood-prone areas to help prepare communities to cope with the devastating effects of climate change. Climate adaptation and action are needed right now." Jamal said.

According to the UN, some seven million people are already in dire need of humanitarian assistance and the consequences of severe flooding will further exacerbate their situation, undermining resilience, coping mechanisms, and access to life-saving services.