WFP head David Beasley said it had happened on Wednesday, the day fighting broke out again following the humanitarian truce agreed in March between Tigrayan forces and the Ethiopian government.

“A group of armed men entered WFP’s compound in Mekelle and forcibly seized 12 tankers filled with over half a million litres of fuel. This fuel had recently been purchased by WFP and arrived just days before it was stolen,” he said.

But Tigray’s regional government called his comments “incendiary” and said it was taking back 600,000 litres of fuel it had loaned to the WFP a few months ago.

“It simply demanded that it be paid back in accordance with the agreement we had,” its statement said.

“The fuel will be used to run basic services, such as hospitals, clinics and other health facilities across Tigray that have been looted, and damaged by the invading forces."

The Tigrayan statement added that it hoped the misunderstanding could be resolved: “We remain committed to co-operating with humanitarian partners as they work hard to address the catastrophic humanitarian crisis raging in Tigray. In this spirit, we are ready to resolve all outstanding issues in discussion with WFP officials.”

UN chief António Guterres has expressed his shock at the resurgence of fighting as in recent months there had been positive signs that peace talks were imminent.

The conflict, which began in November 2020 in Tigray, has led to the deaths of tens of thousands of civilians and left millions in need of food aid and the region has been without basic services such as electricity, telecommunications and banking.

Both sides have blamed each other for igniting the new clashes, which can be heard in the town of Kobo near Tigray’s border in Amhara region.

One female resident of Kobo told the BBC: “The fighting is approximately 20km [12 miles] away from us .We are hearing sounds of heavy weaponry. It can still be heard. The war has been escalated. An additional defence force is entering the area.’’

Tigrayan spokesperson Getachew Reda accused the government of sending “rag-tag militias” to the front to provoke the fighting, saying hostilities were not in Tigray’s interests.

“We were counting on the international community to help open up the blockade and break the siege imposed on the people of Tigray. We need humanitarian aid for our people, we need medicines - we need everything for our people. If anything we are the last people to start fighting at this point in time,” he told BBC Focus on Africa radio.

Asked if he had a message for Prime Minister Abiy Ahmed, he replied: “He cannot fight his way out of the crisis… He definitely risks the disintegration of the Ethiopian state.”

Mr Getachew said the Tigrayan government was happy to sit around a negotiating table as along as there was “unfettered humanitarian access” to Tigray and the constitutional status of Tigray was guaranteed.

“Then the rest will be a question of give and take. We are more than ready to live with any government as long as this basic minimum of Tigrayan people’s right to self-determination is fully observed.”

The BBC has requested a response from the government in Addis Ababa.