The UN humanitarian aid chief has expressed alarm after UN agencies were ordered out of rebel-held parts of the Luhansk region in eastern Ukraine, BBC News reports.

Stephen O'Brien said the agencies had been told to leave by Friday, September 25 and several international non-governmental organisations (NGO) by Saturday.

The Luhansk separatists had earlier banned 10 international humanitarian agencies citing "violations".

In a statement, O'Brien said the "de facto authorities" in Luhansk had ordered the UN agencies and NGOs to leave the area.

He also said all UN agency operations had been suspended in the rebel-held parts of Donetsk.

O'Brien urged the separatists in "both Luhansk and Donetsk to ensure the immediate resumption of UN and international NGO activities".

He warned that restrictions on humanitarian shipments had prevented delivery of some 16,000 tons of vital supplies. "Hospitals cannot perform surgery because they lack anaesthesia. Some 150,000 people are not receiving monthly food distributions," Mr O'Brien said.