KAMPALA, Uganda — Famine has been declared in two counties of South Sudan, according to an announcement by the South Sudan government and three U.N. agencies, which says the calamity is the result of prolonged civil war and an entrenched economic crisis that has devastated the war-torn East African nation.

The official classification of famine highlights the human suffering caused by South Sudan’s three-year civil war and even as it is declared President Salva Kiir’s government is blocking food aid to some areas, according to U.N. officials.

More than 100,000 people in two counties of Unity state are experiencing famine and there are fears that the famine will spread as an additional 1 million South Sudanese are on the brink of starvation, said the announcement.