Sudan has expelled the country director of Save the Children, accusing the British aid agency of breaching Sudanese law and interfering in domestic affairs.
Save the Children confirmed it had received two letters from the ministry on Monday morning expelling their country director Kate Halff and officially warning the organisation.
The charity Oxfam said it had received a letter of warning, which also suggested their country director may be expelled.
Oxfam has been working throughout northern Sudan for 20 years and Save the Children is one of the largest food distributors in Darfur, providing food to more than 300,000 of the almost 2 million in need of aid.
"We can confirm that we have received a letter of warning from the Ministry of Humanitarian Affairs this morning suggesting that the country director may be expelled and we are following up on this with the ministry," Oxfam spokesman Adrian McIntyre told journalists.
A ministry statement said Save the Children had breached Sudanese law by issuing a statement saying a government plane had dropped a bomb close to one of its feeding centres last week in Tawilla town, North Darfur, without waiting for confirmation from African Union ceasefire monitors.
It also rejected a statement from Oxfam criticising a UN Security Council resolution issued in Nairobi earlier this month and said Sudanese law stated that emergency aid organisations should not get involved in political issues.
The council's resolution said it would consider "appropriate" actions if Sudan did not follow through on its commitments to end the violence in Darfur, an oblique threat of sanctions but weaker wording than in previous resolutions.