The United States has said Ethiopia's declaration of a unilateral ceasefire in the Tigray region could be a positive step, if it results in moves to end the conflict.

The State Department urged all parties to allow humanitarian access and speed up the delivery of food assistance.

Hundreds of thousands of people in the region are already facing famine.

Tigrayan fighters have continued to gain ground.

United Nations officials said the rebels entered the town of Shire on Tuesday, after seizing the regional capital Mekelle the day before.

The United States also called for the immediate, verifiable withdrawal of Eritrean troops, who've been supporting Ethiopian federal forces.

The Tigrayans have said they will not stop fighting until they have degraded the capabilities of their enemies.