Aid agencies are unable to restock food, health and other emergency supplies in Ethiopia's northern Tigray region, where federal troops are fighting with local forces, the United Nations warned on Thursday.

Prime Minister Abiy Ahmed embarked on a military campaign against the Tigray People's Liberation Front (TPLF) last week, after accusing the regional rulers of attacking a federal military base.

Telephone lines to the region were still down, the UN Office for the Coordination of Humanitarian Affairs (UN OCHA) said in its latest report on the crisis, hurting aid operations.

‘Transport is not allowed to and from Tigray, as a result of which shortages of basic commodities are reportedly appearing, impacting the most vulnerable first and the most,’ UN OCHA said.

Aid groups were also concerned about the protection of children, women, the elderly and the disabled, from the military clashes, UN OCHA said.

Sudan has received more than 10,000 Ethiopian refugees since the fighting started, the Sudanese government said on Wednesday.

Abiy, who at 44 is Africa's youngest leader, has so far resisted calls by the United Nations, the African Union and others for an immediate ceasefire and negotiations.

There are widespread concerns that the fighting in Tigray could spread to other parts of Africa's second-most-populous country, and to the rest of Horn of Africa region.

Amhara regional state, which neighbours Tigray and has been backing Abiy, called off planned demonstrations against the Tigrayan ruling party.

‘The protest is not timely due to current security concerns,’ said the state's communication office in a statement.