Describing the situation in northern Ethiopia as unpredictable and volatile, the United Nations (UN) on Wednesday urgently called on all parties to allow unimpeded and sustained access for humanitarian aid.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) said the most affected areas are in Tigray, Amhara and Afar regions. The delivery of humanitarian supplies into Tigray is heavily constrained. The only road access is the Semera-Abala-Mekelle corridor.

Between October 6 and 12, 211 trucks carrying humanitarian supplies arrived in Tigray, compared with 80 trucks a week earlier, the humanitarian office said. "While the increased number of trucks is a positive development, this is still insufficient compared to the needs."

Some 897 trucks have entered Tigray since July 12, or only about 14 percent of the trucks needed, the OCHA said, reiterating that 100 trucks are required daily.

There were no fuel deliveries to Tigray since the end of July, the office said. However, 10 fuel tankers waiting in Semera in Afar region have received government approval to proceed into Tigray, and the OCHA hopes they will be able to move to Tigray with the next convoy.

More than 146,000 people received food aid last week. But at least 870,000 people on an average week need food assistance. The partners need to serve 5.2 million people within a six-week cycle.

Emergency water was delivered by truck to about 143,000 people last week, down from about 193,000 people a week earlier.

In the Afar region to the east of Tigray, and Amhara to the south, humanitarian partners are scaling up their responses, the OCHA said.

Since early August, the OCHA has reached about 639,000 people with food assistance in the accessible areas of Amhara and about 72,000 internally displaced people in Afar.