Russia’s decision to send more than 100 aid lorries into war-torn eastern Ukraine without permission has been widely condemned in the West.
The European Union and the US called for them to be withdrawn, calling it a violation of Ukraine’s sovereignty. Nato said it would deepen the crisis.
But Russia said further delays were unacceptable – and also denied that its troops and artillery were in Ukraine.
The first trucks have now reached the besieged rebel-held city of Luhansk.
The UN is to hold an emergency meeting to discuss the convoy’s entry, which Ukraine has described as an “invasion”.
Meanwhile, Lithuania – a fierce critic of Russia’s actions in Ukraine – has said its honorary consul in Luhansk has been murdered “by terrorists”, a term routinely used by Ukraine for pro-Russian separatists.
In a strong statement, Nato chief Anders Fogh Rasmussen said Friday’s developments were “even more worrying as they coincide with a major escalation in Russian military involvement in eastern Ukraine since mid-August, including the use of Russian forces”
Ahead of the UN Security Council meeting, Russia’s UN ambassador Vitaly Churkin said they had lost patience with Ukraine’s chain of command and that Russia had had to act to save perishable goods and he hoped the ICRC would help now distribute the aid.
“We regret if some Ukrainian officials are trying to stir the situation and create some political crisis, which is there but not for the reason of the Russian humanitarian convoy moving to the people in need,” he said.
Churkin rebuffed Nato’s accusations of military support for the Ukrainian separatist forces, saying the body had no proof – adding there were no Russian troops or artillery on Ukrainian soil.
He also lambasted Lithuania’s UN for “torpedoing all productive, constructive initiatives we’ve had in the Security Council”, in particular Russia’s proposal calling for a ceasefire.
His Ukrainian counterpart at the UN, Oleksandr Pavlichenko, said border guards had begun inspecting of some of the lorries on Thursday afternoon, but the Russians had decided to go ahead without waiting for them all to be cleared.
Foreign journalists were allowed to look into the Russian lorries earlier this week, and found they contained humanitarian supplies such as baby food and cereals.
Reporters at the scene saw rebel fighters in front of the convoy as it crossed the border near the town of Kamensk-Shakhtinsky.
Four months of fighting in eastern Ukraine have left more than 2,000 people dead and caused more than 330,000 people to flee their homes.