The death toll from floods in Nigeria this year has increased to 603 as local authorities race to provide relief to hundreds of thousands of people being evacuated from their submerged homes.

More than 1.3 million people have been displaced by the disaster, which has affected people across 33 of Nigeria’s 36 states, the humanitarian affairs ministry said late on Sunday.

At least 3,400sq km (1,300sq miles) of land has been inundated, worsening fears of food supply disruptions. Conflict already has threatened production in the northwest and central regions of Nigeria, which produce much of what the country eats.

President Muhammadu Buhari directed “all concerned to work for the restoration of normalcy”, according to a statement issued by his office.

All Federal agencies dealing with rescue and disaster management have been directed to scale up response and intervention efforts to support the victims of flooding across the country, as well as all the affected State Governments - 33 States so far affected, and the FCT.

— Muhammadu Buhari (@MBuhari) October 16, 2022

Nigeria experiences annual flooding, especially in its coastal areas, but this year’s floods are the worst in more than a decade. Authorities blame the disaster on the release of excess water from Lagdo Dam in neighbouring Cameroon and on unusual rainfalls.

Al Jazeera’s Ahmed Idris, reporting from Yenagoa, the capital of Bayelsa state in southern Nigeria, said people are fleeing to the city in the hopes of getting help from authorities.

“The bad news is, it’s been pouring down for the past few days and the rains are expected to keep coming down for the coming days,” Idris said.

“The water levels are rising to an alarming level,” he said. “The ferocity of the flow of water has also intensified. The flood waters from upstream are continuing to come this way.”

The flooding has worsened a humanitarian crisis in Nigeria, where violence, especially in the troubled northern region, has displaced more than three million people, according to the Internal Displacement Monitoring Centre.

Sadiya Umar Farouq, the minister of humanitarian affairs, warned that five states are still at risk of experiencing floods until the end of November.

“We are calling on the respective state governments, local government councils and communities to prepare for more flooding by evacuating people living on flood plains to high grounds,” Farouq said.

Last week, Buhari allocated 12,000 metric tonnes of grain for the flood victims, the humanitarian affairs minister said.