The humanitarian crisis in Ethiopia is escalating as the fighting in the north of the country continues to drive the displacement of thousands people, the UN reports.

More than 50,000 refugees have now crossed the border to Sudan to escape fighting in Ethiopia’s Tigray region, but the number of arrivals is reportedly slowing because of barriers which prevent them fleeing, including robbery and violence by armed groups.

The UN has called for “unfettered access” to the region to support people in need, and has reported increasing concern for some 96,000 Eritrean refugees caught up in the conflict.

The Ethiopian government says it is returning thousands of Eritreans back to the camps in Tigray from which they fled, saying the area is now safe as its military campaign against the regional government is completed.

However, aid groups say that food is in short supply in the camps, and there are continued reports of violence in the region.

The UN refugee agency UNHCR said it has received ‘an overwhelming number’ of reports of refugees being killed or forcibly returned to Eritrea, which would constitute a ‘major violation’ of international law.

UNHCR has now registered nearly 50,000 Ethiopian refugees who have crossed into eastern Sudan, with some reporting having to evade armed groups to reach safety.

Since December 6, the number of refugees escaping ongoing conflict in the northern Tigray region have been trending downward to under 500 per day.

The recent groups coming from areas deeper inside Tigray are arriving weak and exhausted, some reporting they spent two weeks on the run inside Ethiopia as they made their way to the border.

They have reported being stopped by armed groups and robbed of their possessions. Many have spent time hiding in fields and bushes to avoid being spotted.

The UNHCR says it is worried about the safety and condition of the Eritrean refugees in Tigray that have been caught in the conflict and have had no access to services and supplies for more than a month.

It has voiced alarm over the forced return of Eritrean refugees to camps they fled from in Ethiopia’s embattled Tigray region. 

The Ethiopian government said in a statement it was sending back Eritrean refugees who had fled from Tigray to Addis Ababa in recent weeks.

The government says it is returning thousands of refugees who ran from camps in its Tigray region as war swept through, putting them on buses back to the border area with Eritrea, the country the refugees originally fled.

It’s a “disturbing” and “alarming” move, according to the UN, which does not have access to the camps.

The news came as the United States said it believes Eritrean troops are active in Ethiopia, which it called a “grave development”.

“We are aware of credible reports of Eritrean military involvement in Tigray,” a State Department spokesperson said in an email.

Meanwhile, aid agencies say they believe food is in short supply at the camps and have also expressed concern about reports of continued violence in some areas. 

“The government of Ethiopia has said it will guarantee humanitarian access to the Tigray region for the UN and its partners.

While a signed agreement is one first step, it still needs to be implemented in a way that ensures safe and unhindered access for humanitarian workers in accordance with the principles of neutrality and impartiality, the UN says.