The EU's humanitarian chief on Tuesday condemned Ethiopian authorities for cutting off the war-torn Tigray region after announcing a unilateral ceasefire.
"There is an embargo on flights to Tigray. Internet and telecommunications have been cut," EU crisis management commissioner Janez Lenarcic told the European Parliament.
"Telecommunication outlets that are essential to humanitarian operators have been confiscated.
"Humanitarians are prevented from entering Tigray and from delivering much needed assistance. It is not a ceasefire, it is a siege, and starvation is used as a weapon of war."
Tigray has been the scene of fighting since Ethiopian Prime Minister Abiy Ahmed sent the army early in November to topple dissident regional authorities.
The 2019 Nobel Peace Prize winner accused them of orchestrating attacks on Ethiopian military bases.
After early successes and a premature declaration of victory, government forces were involved in a months-long battle with the Tigray Defence Forces.
The Ethiopian army was backed by troops from the neighbouring Amhara region and soldiers from Eritrea, which borders Tigray.
In late June, the TDF recaptured the capital Mekele, which had held by the Ethiopian army since November 28.
The government in Addis Ababa immediately declared a unilateral ceasefire.
The rebels in Tigray on Sunday accepted "a ceasefire in principle" but posed strict conditions for it to be formalised.
Mr Lenarcic said that despite the government announcement, "unspeakable atrocities continue also to be reported, with credible allegations of serious violations of international humanitarian law, human rights law and international refugee law".
"Tigray borders must be opened to humanitarian relief operations. Relief actors need to be able to carry out their work independently, freely and in safety at all times," he said.
"Up to 900,000 civilians" are facing famine conditions in Tigray and another million "are one step below famine".
The EU has so far steered clear of imposing sanctions on Ethiopia over the crisis, but last year it postponed nearly €90 million ($105m) in budget support to the country.