Tens of thousands of South Sudanese migrants have escaped to neighboring Sudan since the start of the year in a desperate bid to flee the famine that has gripped part of their home country, the UN's refugee agency said on Sunday.

The United Nations High Commissioner for Refugees (UNHCR) warned that tens of thousands more expected to flee as food security in the world's youngest country continues to deteriorate.

Last week, the UN declared that some 100,000 people face starvation in the world youngest country, while another million are on the brink of famine. By July, some 5.5 million people, almost half the population, will be without a reliable source of food. The crisis marks the first time the world has confronted such a catastrophe in six years.

"The food security situation is expected to deteriorate further in coming months," the UNHCR said in its report.

The report also stated that refugees arriving in Sudan have reported walking for five to seven days to reach the border, while 90 percent of new arrivals are women and children. "Many arrive exhausted and in poor health, often with critical levels of malnutrition," it said.

Funding remains a key barrier to battling the crisis, the UNHCR said. The agency has appealed for $166.65 million (157.7 million euros) to meet the needs of South Sudanese refugees. However, inter-agency partners have so far only been able to raise around five percent of the necessary funds.

A 'man-made' crisis

Aid groups have largely slammed South Sudan's food crisis as "man-made," caused by years of civil war and bloodshed. In 2013, just two years after the country gained independence from Sudan, President Salva Kiir accused his rival and former deputy Riek Machar of plotting a coup against his government. Subsequent in-country fighting along ethnic lines has left thousands dead and seen some three million people displaced.

Conflict has also left the oil-rich nation impoverished. South Sudan's agricultural sector has been paralyzed, inflation has soared by around 800 percent and relief agencies remain cut-off from many of the worst-hit regions.

Pope Francis weighing South Sudan trip

Pope Francis said Sunday that he was a considering a request from his bishops to visit the famine-struck country this year.

Responding to a question about Christian churches in Africa, Pope Francis said: "My aides and I are studying the possibility of a trip to South Sudan." The Pope added that the trip would likely only last a day, which Vatican sources said would namely be for security reasons.

dm/jr (AP, dpa, AFP)