UN aid agency suspends all convoys to Syria

The suspension of aid deliveries would hold pending a review of the security situation in Syria, Jens Laerke, spokesman for the UN humanitarian aid agency, OCHA, said.

The UN aid coordinator had received needed authorisations from the Syrian government in recent days to allow aid convoys to proceed in Syria, Laerke said.

He said it's "a very, very dark day ... for humanitarians across the world".

An infuriated United Nations warned Monday night's attack could amount to a war crime.

"Let me be clear: if this callous attack is found to be a deliberate targeting of humanitarians, it would amount to a war crime," aid chief Stephen O'Brien said.

"Our outrage at this attack is enormous," the UN envoy for Syria, Staffan de Mistura, told reporters.

"The convoy was the outcome of a long process of permission and preparations to assist isolated civilians."

Rights groups also voiced outraged over the attack.

"There is absolutely no excuse for the shocking attack yesterday on an aid convoy in rural Aleppo," Andy Baker, Oxfam’s leader for the Syria Crisis Response said.

"The aid workers on the convoy were delivering much needed help to thousands of people and Oxfam is appalled and outraged that many of them lost their lives doing so."

Aid deliveries to desperate civilians were a key element of the US-Russia deal.

But there were only three known aid delivery operations during the week-long truce: to Moadamiyet al-Sham near Damascus on Sunday and to both Talbisseh and Orum al-Kubra on Monday.

Cross-border aid for besieged civilians in eastern parts of Aleppo city never entered Syrian territory.

Syria's military unilaterally announced the end to the truce on Monday night, accusing rebels of more than 300 violations and failing to "commit to a single element" of the deal.

Agencies contributed to this report