South Sudanese refugees are pouring across the border into neighbouring Sudan, seeking safety in the country from which South Sudan seceded a few years ago.
Sovereignty was achieved in 2011 after 99 per cent of South Sudanese voted to break away from Sudan following a decades-long war for independence.
"It is peculiarly tragic, and a devastating commentary on South Sudan, that hundreds of thousands of South Sudanese are fleeing their independent land to seek sanctuary and sustenance in the lands of their former oppressor," Sudan expert Dr Alex de Waal commented on Thursday.
More than 375,000 South Sudanese -- nearly 90 per cent of them women and children -- have fled to Sudan since the outbreak of civil war in 2013. Only Uganda, with 883,000 registered arrivals, hosts more South Sudanese refugees than does Sudan.
The flight into Sudan is accelerating, the United Nations refugee agency reported on Thursday.
Some 23,000 South Sudanese crossed into Sudan last month, bringing the total so far this year to 108,000.
The UN estimates that up to 50,000 additional South Sudanese could flee to Sudan in the next month as fighting and hunger intensify in areas near the border.
The UN lacks the resources needed to respond adequately to this mass exodus. A plea for $167 million to care for South Sudanese refugees in Sudan is less than 10 per cent funded, the UN says.
The Khartoum-based Sudan government has been cooperating with efforts to assist refugees from the territory it formerly ruled.
National authorities have also agreed to open three "humanitarian corridors" into South Sudan to enable food and other aid to reach vulnerable civilians more quickly.
Dr de Waal, director of the World Peace Foundation at a US university, predicted that Sudan, despite its "weak" economy, will eventually be able to absorb the growing numbers of South Sudanese refugees.
"They will of course be a strain on local resources where they first arrive," he said. But Sudan has long experience in employing southern Sudanese migrants, Dr de Waal pointed out.
"They have worked as labourers in agricultural projects, as servants in private houses, in the construction industry and in a variety of low-paid jobs," he noted.