The head of the World Health Organization has said he expects "many more" deaths in Sudan due to a lack of essential services as fighting continues in the country in Northeast Africa.

WHO Director-General Tedros Adhanom Ghebreyesus said on Wednesday that there will be "many more deaths due to outbreaks, lack of access to food and water and disruptions to essential health services, including immunization" in Sudan.

He said only 16 percent of health facilities are functioning in the Sudanese capital, Khartoum, and paramedics, nurses and doctors are unable to access injured civilians.

Tedros said the WHO estimates a quarter of the lost lives could have been saved with access to basic hemorrhage control.

Gun battles are reportedly ongoing in Sudan between the Sudanese Armed Forces and the paramilitary Rapid Support Forces despite a newly agreed 72-hour ceasefire.

The White House said on Wednesday that a second American has been killed in Sudan.