The International Organization for Migration announced that one of its employees was killed in the fighting in the city of El Obeid, in South Sudan, on Friday, after his vehicle was caught in the middle of a crossfire.

This employee is the fourth employee of the United Nations to be killed since the start of the conflict in Sudan on Saturday, as three employees of the World Food Program were killed in the state of North Darfur in eastern Sudan.

"It is with a heavy heart that I confirm the death of a dedicated IOM staff member in Sudan this morning (Friday) after the car he was traveling in with his family got stuck south of El Obeid city amid an exchange of fire between two warring parties," said the head of the organization, Antonio Vitorino, in a statement.

"I am deeply saddened by the death of our fellow humanitarian worker, and I share with his wife, newborn baby, and our mourning staff in Sudan," he added.

The employee was a 49-year-old Sudanese national who was driving his own vehicle, a spokesman for the International Organization for Migration told AFP.

Vitorino stressed that the safety of staff is his top priority and that he is ready to cooperate with other UN agencies to update their security response.

"The recent outbreak of violence has forced the International Organization for Migration to suspend its humanitarian operations in Sudan," he said, adding, "All parties must ensure the safety of humanitarian workers and allow their unfettered access so that they can assist the most vulnerable."

He pointed out that about 3.7 million people have been internally displaced in Sudan and that before the recent outbreak of violence, 15.8 million people (one-third of the population) were in need of humanitarian assistance.

The clashes left more than 400 dead and 3,500 wounded, according to a new toll reported by the World Health Organization.