NAIROBI - An estimated 32.1 million people in East Africa would need food aid by the beginning of 2016 due to El Nino phenomenon, the UN has said.

El Nino phenomenon featuring heavy rains would worsen food security in the coming months in the region, the UN Office for Coordination of Humanitarian Affairs (OCHA) said in a report released Thursday in Nairobi.

Excessive rainfall could cause localized displacement, impede crop production and increase post-harvest losses, according to the report.

The report said the most vulnerable people were adversely impacted by economic shocks such as rising food prices in South Sudan and Ethiopia.

It said the humanitarian community was facing restricted humanitarian access and shortfalls in funds.

"Up-to-date contingency and response plans, front-loading funding, early action, especially nutrition intervention and continued investment in resilience is key," said the report.

It warned that excessive rain could lead to flooding, affecting some 2 million people, especially in Kenya and Somalia.

Of particular concern, the report said, is the flood-prone Shabelle and Juba Valleys in Somalia, Rift Valley in Kenya, and northern Tanzania -- from the Victoria Basin to the coast.

"This could result in localized displacement and increasing the incidence of communicable diseases," it said.

It said excessive rainfall could trigger outbreaks of waterborne diseases such as cholera and typhoid, as well as vector-borne diseases such as malaria.

"Cholera remains a persistent concern in at least five countries, and high Crude Fatality Rate rates in Kenya, South Sudan and DR Congo," it said.

Historically, El Nino phenomenon had "significant" impacts in the region: 1.7 million people were either displaced or lost their property and livestock during the 1997/8 and 2007 El Nino, according to the UN's Food and Agriculture Organization.

According to the report, humanitarian requirements for East Africa exceeds 5.7 billion U.S. dollars and are set to increase further in 2016, yet only 43 percent have been funded.