Diplomatic efforts to douse an international firestorm over claims that Ukraine's forces destroyed Russian military vehicles ratcheted up today as Moscow demanded that Kiev allow its mammoth aid convoy to cross the volatile border.
Moscow and Kiev's foreign ministers prepared for an urgent meeting tomorrow with their French and German counterparts after the United States blasted Russia for its "extremely dangerous" escalation of the crisis in Ukraine.
French President Francois Hollande, meanwhile, urged Ukraine to show "restraint and good judgement" as it pushed on with a brutal offensive to oust insurgents after four months of fighting that has killed over 2,000 people and left the region facing a humanitarian disaster.
The latest spike in tensions came after Ukrainian President Petro Poroshenko claimed his troops had blown up part of a small Russian military convoy that British media spotted breaching the porous frontier on Thursday.
Russia dismissed the claims as "fantasies", its latest denial of persistent allegations from the West that it is arming the rebels.
Amid the international slanging match, some 280 trucks packed with what Russia claims is humanitarian aid waited for a third day some 30 kilometres from a rebel-held border post as Moscow and Kiev haggled over letting it across.
The West and Kiev fear the convoy could be a "Trojan horse" to bolster the flagging pro-Kremlin rebellion in eastern Ukraine or provide Moscow with an excuse to send in the 20,000 troops that NATO says it has amassed on the border.
Russia's foreign ministry has repeatedly demanded in recent days that Kiev cease fire in order for the aid to reach residents of blighted cities in the east who have been stuck for days without water or power.
AFP correspondents at the border heard blasts from the Ukrainian side and saw Moscow's military hardware rumble along Russian territory close to the frontier.
Ukraine says it has sent scores of border officials to the Russian side to scour aid cargo but insists they are waiting for permission from the Red Cross to start work.
A spokeswoman for the International Committee of the Red Cross -- which is meant to be overseeing the operation -- told AFP that so far no inspections have started as negotiations continue.
"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.
