The number of South Sudanese people that have sought refuge in neighbouring Uganda has now hit the one million mark, the United Nations has said.

According to the UNHCR, an average of 1,800 South Sudanese people have been arriving in Uganda daily in the past 12 months, with another one million seeking refuge in Sudan, Kenya, Ethiopia, Congo and Central African Republic.

Ugandan officials have warned that this continuous flow of South Sudanese refugees into the country is putting a strain on its resources.

The UN earlier this year appealed to the international community to offer donations to help the refugees.

South Sudan descended into war in December 2013 following President Salva Kiir’s accusations that his then-deputy Riek Machar was plotting a coup against his government. Machar denied the allegations but then went on to mobilize a rebel force to fight the government.

A peace deal signed in 2015 has continuously been violated by the warring parties, with the UN earlier this year warning of the possible eruption of genocide in the country.

The world agency lists South Sudan as Africa’s biggest refugee crisis, and third wordwide after Syria and Afghanistan.

The U.N. says at least $674 million is needed to support South Sudanese refugees in Uganda this year, although only a fifth of that amount has been received.

The money is needed to provide basic services, including stocking clinics with medicines and putting up schools. Aid agencies say classroom sizes in the few available schools often exceed 200 pupils, and other children have dropped out because the nearest schools are miles away.