Ukraine's crisis entered dangerous new territory today with Kiev claiming its forces destroyed a Russian military convoy, while the US warned Moscow over its "provocative" efforts at destabilisation.

Moscow and Kiev's top diplomats agreed to an urgent meeting with their French and German counterparts tomorrow in an attempt to calm the soaring tensions, as wrangling continued over the fate of a mammoth Russian aid convoy parked up close to the Ukrainian frontier.

The US National Security Council warned of an "extremely dangerous and provocative" escalation in the crisis by Russia after Ukrainian President Petro Poroshenko claimed his troops had blown up part of small Russian army convoy -- separate from the humanitarian convoy -- that breached the border.

Russia dismissed the claim as "fantasies," its latest denial of persistent allegations from the West that it is arming the rebels.

But the European Union piled the pressure on Moscow by insisting it "put an immediate stop to any form of border hostilities, in particular to the flow of arms, military advisers and armed personnel into the conflict region".

The humanitarian situation in war-torn east Ukraine has deteriorated still further as four months of fierce clashes that have killed over 2,000 people and left people without water and basic services raged on.

Moscow has sent nearly 300 trucks of what it claims is humanitarian aid to eastern Ukraine. The West and Kiev fear it could be a "Trojan horse" of arms and possibly even soldiers bound for the restive east of the country.

The Russian convoy has been parked since Thursday about 30 kilometres from the border with Ukraine's Lugansk region, as Kiev and Moscow continued to haggle over how it would cross into rebel-held territory.

A Red Cross spokeswoman in the border zone told AFP today that so far the organisation has not inspected any of the trucks, waiting for both sides to give a green light.

"There was a meeting this morning between the Ukrainians and the Russians. We did not participate," said Galina Balzamova. "We are still waiting for agreement" between them, she added.

The US warned Moscow against sending "vehicles, person, or cargo of any kind into Ukraine, under any pretext" without Kiev's permission.