John Kerry insists Syria ceasefire ‘not dead’ as UN suspends aid

The United Nations suspended aid convoys into Syria a day after an air strike hit relief trucks, leaving diplomats scrambling to maintain a US-Russian peace plan for the country.

Ban Ki-moon used his farewell address to the UN General Assembly to denounce the “sickening, savage and apparently deliberate attack” on the UN food relief convoy that killed at least 20 people.

The outgoing secretary general told world leaders who had gathered in New York that the dead aid workers were heroes and said “those who bombed them were cowards” before calling for accountability for crimes committed in the war.

“Just when you think it cannot get any worse, the bar of depravity sinks lower,” he said.

US secretary of state John Kerry said on Tuesday morning that "the ceasefire is not dead" and Russian officials also insisted that the plan to halt fighting had not yet been abandoned.

However, with events on the ground continuing to undermine the US-Russian plan, ministers from other governments said it would be very hard to revive the agreement.

“We have to be honest: the US-Russian negotiation has reached its limits,” said French foreign minister Jean-Marc Ayrault. And German foreign minister Frank-Walter Steinmeier said diplomats were trying to see if there was a way to restart negotiations or if the situation had become “hopeless”.

The ministers were speaking after a meeting in New York of the governments involved in the Syrian conflict, which took place on the margins of the general assembly.

The US said the meeting agreed “there was still an imperative to pursue a nationwide cessation of hostilities”, and that ministers would meet again later this week.

The flurry of diplomatic activity came as furious UN officials warned that Monday night's air strike near Aleppo, in which 18 of 31 trucks in the aid convoy were destroyed, was 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,” said UN aid chief Stephen O’Brien.

Two other aid agencies also suspended their operations.

US officials and opposition activists blamed the attack on warplanes belonging to Syria or Russia, which has intervened militarily on president Bashar al-Assad's behalf. But Moscow and the Syrian government denied responsibility and hinted that local rebels were to blame.

Igor Konashenkov, spokesman for the Russian defence ministry, said video of the convoy showed no evidence of missile strikes. He said it could have been a fire, according to a statement reported on Tass, the Russian state news agency.

‘Hard to reach’

The attack on the convoy is a blow to the ceasefire as well as to desperately needed humanitarian operations for hundreds of thousands of Syrians struggling to survive in areas under siege or surrounded by fighting.

According to the UN, 4.5 million people are living in areas that are “hard to reach”.

The Siege Watch group says a million Syrians are under blockade.

Privately, humanitarian officials said they had already been struggling to assure drivers the convoys would be safe from attack. The argument will be even more difficult to make now.

The International Committee of the Red Cross called the strike an “attack on humanity” as it suspended its aid convoys. It said 20 people had been killed, most of them civilians.

Omar Barakat, the local head of the ICRC-supported Syrian Arab Red Crescent, was named as one of the victims.

Just before it was struck, the convoy delivered aid to 78,000 people in the town of Urum al-Kubra in Aleppo province.

Pictures uploaded on social media by activists on Tuesday showed charred, overturned trucks and bottles of medicine spilled on bloodstained ground.

Copyright The Financial Times Limited 2016/Guardian service