On Monday the UN said around 35,000 Sudanese refugees have crossed the border into South Sudan over the last three weeks to escape fighting between the government and rebel movements, increasing the pressure on the humanitarian aid available.

The UN refugee agency (UNHCR) said the 35,000 people arrived from Blue Nile state and have joined around 70,000 Sudanese refugees already living in the South Sudanese camps.

In a statement UNHCR spokesman Gutierrrez said ‘the number of refugees is a significant increase with many living in alarming humanitarian conditions.’

He said some refugees are forced to eat leaves to keep going.

The emergency relief organisation Doctors Without Borders has said 2,000 refugees are crossing the border every day and water will soon run out in the camps.

The organisation said refugees are arriving exhausted after spending months in the open, hiding from fighting and crossing the border, forced to walk for days and sometimes weeks.