NAIROBI, April 25 (Thomson Reuters Foundation) - Flash floods in drought-stricken parts of Ethiopia have killed people and livestock and are blocking food aid deliveries to hungry communities, a charity said.

Ethiopians have been waiting for the spring rains to replenish water sources and to plant crops after the most severe drought in decades pushed more than 10 million people into hunger.

But many livestock, weakened by the drought, have died following heavy rains in Ethiopia's remote Somali and Afar regions, the Norwegian Refugee Council (NRC) said on Sunday.

"Not only are families losing their remaining livestock, but the heavy rain is making the roads inaccessible," said Mohamed Hassan, who heads NRC's work in the Somali region.

"Roads are turning into raging rivers and trucks carrying food assistance are unable to reach many communities.

"If people don't get aid I am afraid that human lives might be lost," he said in a statement.

Some 28 people were killed by flash floods in early April, the majority when a river passing through Jijiga, the capital of Somali region, burst its banks, the government said.

The two eastern regions, among the worst hit by the drought, are mainly home to herding communities. Cattle, sheep and goats often die after floods because infectious diseases increase and vegetation becomes toxic.

The government and aid agencies are revising upwards a joint appeal in December for $1.4 billion as the number of districts suffering a humanitarian emergency has widened.

The crisis is expected to deepen until August when people hope to harvest crops they will plant in June to catch the summer rains.

Floods can also contaminate water sources, causing diseases like cholera.

Ethiopia regularly suffers hunger crises as eight out of ten people are farmers who depend upon the rains.

"We will see this situation again and again," said Hassan. "We must not only hand out food, but also help people find alternative livelihoods."

(Reporting by Katy Migiro; Editing by Ros Russell; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights and climate change. Visit http://news.trust.org to see more stories.)