The Eritrean government has expelled a number of international aid agencies.
Eritrea is seeking to reduce its reliance on food aid
Letters have been sent to at least three agencies, including US charity Mercy Corps, the Irish agency Concern, and a British NGO, Acord.
No reason was given for the move, only that they had not met the requirements for operational permits.
At least one in three Eritreans is seriously short of food, as the country suffers from a drought which has hit the whole of the Horn of Africa.
President Isaias Afewerki has repeatedly called on his people to practise self reliance.
"While thanking your organization for the contribution it has made to relief and rehabilitation programs in Eritrea in the past years, the Ministry kindly officially informs you that the registration certificate is recalled and requests the termination of your activities," one of the letters from the Ministry of Labour and Human Welfare says.
The aid agencies say they are hoping to discuss the issue with the government.
But Eritrea has gradually reduced its relations with the entire world community.
The country turned down a crop assessment mission from the United Nation's agencies last year.
Then, in September food warehouses were closed, cutting the number of people receiving aid from 1.3m to 72,000.
Recently Eritrea has clamped down on UN peacekeepers patrolling its border with Ethiopia and expelled Western UN staff.
The neighbours fought a brutal war between 1997-2000 which ended with a peace agreement committing both sides to abide by the ruling of an international tribunal that decided where the border should run.
However, Ethiopia refused to let it be demarcated without further discussion and Eritrea has been urging the international community to put more pressure on Ethiopia to comply with the ruling.
At talks intended to end the deadlock last weekend, the Boundary Commission told both countries it would resume the demarcation process where it left off some years ago.