Fighting in Sudan has prompted a wave of people to seek sanctuary in neighbouring countries.
According to the UN High Commissioner for Human Rights, "hundreds of thousands" are expected to flee the country.
Around 14,000 people, the majority South Sudanese citizens, have already arrived in South Sudan, a UN spokesperson told AFP on Saturday.
"The ongoing fighting in Sudan is expected to trigger further displacement both within and outside the country. We're scaling up to assist people seeking safety," the UN refugee agency UNHCR tweeted.
Here is an overview of the situation:
- Refugees, IDPs within Sudan -
Sudan hosted 1.13 million refugees before the conflict started -- one of the largest refugee populations in Africa.
Of those, 800,000 are South Sudanese, with Eritreans the second-largest group, numbering 126,000. There are also 58,000 Ethiopians, mainly hosted in two eastern camps.
Axel Bisschop, the UNHCR's representative in Sudan, said Friday that up to 30,000 people, mainly South Sudanese refugees, had moved south from Khartoum to White Nile State, closer to their own border.
Ethiopian and Eritrean refugees are also moving closer to their own borders, he added.
Sudan counts around 3.7 million internally displaced persons, mostly in the volatile western Darfur region.
The UN's International Organization for Migration (IOM) said Tuesday that "at least 75,000 people have been internally displaced in Sudan by the crisis".
It said that in the South Darfur region, up to 37,000 people are thought to have been displaced across Nyala town.
- Fleeing abroad -
Sudan shares a border, in order of length, with South Sudan, Chad, the Central African Republic, Egypt, Eritrea, Ethiopia and Libya.
UNHCR is planning for three scenarios: Sudanese refugees fleeing to neighbouring countries; refugees hosted by Sudan returning home and refugees hosted by Sudan moving to other neighbouring countries.
"So far, the most significant cross-border movements in the region have been Sudanese fleeing to Chad and South Sudanese refugees returning to South Sudan," the agency said.
- Chad -
UNHCR spokesman Matt Saltmarsh said at least 20,000 people had crossed into Chad, of which around 5,000 have been formally registered so far.
The aid agency CARE International cited border area community leaders as saying more than 42,000 people had crossed.
UNHCR is expecting the number to rise to up to 100,000 people "in the worst-case scenario".
Many had fled to villages only five kilometres (three miles) from Sudan, "and more are expected to arrive in the coming days," the agency said.
The IOM's Chad mission chief Anne Kathrin Schaefer said: "The majority of those arriving are in dire need of basic humanitarian aid, namely food, water and adequate shelter."
The looming rainy season will make it harder to reach the border area with aid.
More than 400,000 Sudanese refugees are already hosted across 13 camps and among local communities in eastern Chad.
- Egypt -
More than 14,000 Sudanese refugees have crossed the border, the Egyptian foreign ministry said Thursday, plus a further 2,000 nationals of 50 other countries.
Refugees making it to Cairo reported leaving with few belongings, food, water or cash on the treacherous journeys, having paid small fortunes for scarce bus tickets out of the war zone amid crippling fuel shortages.
UNHCR said it was working with the four-million-strong Sudanese community in Egypt to get a better sense of the new arrivals and to identify support needs.
- South Sudan -
At least 14,000 people had crossed the border to South Sudan, UNHCR spokesperson Shabia Mantoo told AFP on Saturday.
Marie-Helene Verney, UNHCR's representative in South Sudan, said Tuesday "the most likely scenario is 125,000 returns of South Sudanese refugees into South Sudan, and 45,000 refugees."
- Ethiopia -
More than 3,500 people arrived in Ethiopia between April 21 and 25, Eric Mazango, the IOM's spokesman in the country, told AFP on Thursday.
Citizens of more than 35 countries have entered Ethiopia, with Turks accounting for more than 40 percent, followed by Ethiopians at 14 percent.
- Central African Republic -
On Monday, UN peacekeepers said a group of 500 mostly women and children had crossed the border, with local authorities saying they needed food, water and shelter. By Friday, total arrivals had increased to 1,300, according to UNHCR.
- Libya and Eritrea -
The Libyan authorities have noted no significant increase of entries from Sudan. UNHCR had no information on movement into Eritrea.